Catch2 compatibility means the API tests are written in: the macros, such
as TEST_CASE and REQUIRE, and the Catch:: namespace. It does not mean
Catch2's build names or header paths. find_package(Catch2) found Catch3,
and a project using both frameworks met two packages, two sets of targets,
two Catch.cmake modules and two catch2/ header trees with the same names.

Build names:
- CMake: project and package Catch3, targets Catch3::Catch3 and
  Catch3::Catch3WithMain, libraries Catch3 and Catch3Main, options
  CATCH3_*, lib/cmake/Catch3 with Catch3Config, and pkg-config catch3 and
  catch3-with-main. The version is Catch3's, 0.3.0, compatible within a
  minor version.
- The CMake scripts are Catch3.cmake (catch3_discover_tests),
  Catch3AddTests.cmake and Catch3ShardTests.cmake
  (catch3_add_sharded_tests); the helpers they define at ctest time have a
  catch3_ prefix. ParseAndAddCatchTests.cmake, deprecated upstream, is gone.
- Bazel //:catch3 and //:catch3_main, Meson catch3 and catch3-with-main
  (with override_dependency), Xmake catch3 and catch3_main, Premake Catch3
  and Catch3WithMain. Visual Studio projects get GUIDs of their own.
- The Progmasoft::Catch3 target and package are gone: property testing
  and snapshots are part of Catch3::Catch3. Their sources now build with
  the library's warning flags, so property failures are built field by
  field (no missing initializers) and the default property name is a
  thread-local pointer to the name its scope owns (no global destructor).

Headers: the engine moved from src/catch2 to src/Progmasoft/Catch3 with
Progmasoft names, so <catch2/catch_test_macros.hpp> is
<Progmasoft/Catch3/TestMacros.hpp>, <catch2/matchers/catch_matchers_string.hpp>
is <Progmasoft/Catch3/Matchers/String.hpp>, and interface headers are named
after their interface, such as Interfaces/IConfig.hpp. Include guards
became #pragma once. The installed headers go to include/Progmasoft.
src/Progmasoft/Context.cpp is StrategyContext.cpp, so no two sources share
a file name.

tools/scripts/upstreamFiles.txt lists the files that come from Catch2.
The license check expects BSL-1.0 on them and Progmasoft's header on the
rest of src/Progmasoft; the convenience-header check, the amalgamation
script and the surrogate tests take the engine's headers from it. The
amalgamated files are regenerated. The header-guard workflow checks for
#pragma once instead of checkguard.

Documents, the README and the release notes describe the new names.

Closes #2954
Closes #3010

This means that:
1) Scoped messages are always removed at the end of their scope,
   even if the scope ended due to an exception.
2) Scoped messages outlive section end, if that section's scope is
   enclosed in their own.

Previously neither of these were true, which has led to a number
of surprising behaviour, where e.g. this:
```cpp
TEST_CASE() {
    try {
        INFO( "some info" );
        throw std::runtime_error( "ex" );
    } catch (std::exception const&) {}

    REQUIRE( false );
}
```
would print "some info" as the message for the assertion, while this:
```cpp
TEST_CASE() {
    INFO("Hello");
    SECTION("dummy") {}
    REQUIRE(false);
}
```
would not print out "Hello" as the message for the assertion.

This had an underlying reason, in that it was trying to helpfully
keep the messages around in case of unexpected exceptions, so that
code like this:
```cpp
TEST_CASE() {
    auto [input, expected] = GENERATE(...);
    CAPTURE(input);
    auto result = transform(input); // throws
    REQUIRE(result == expected);
}
```
would report the value of `input` when `transform` throws. However,
it was surprising in practice and was causing various issues around
handling of messages in other cases.

Closes #1759
Closes #2019
Closes #2959

* bugprone-branch-clone
* bugprone-copy-constructor-init
* bugprone-empty-catch
* bugprone-sizeof-expression
* bugprone-switch-missing-default-case
* bugprone-unused-local-non-trivial-variable
* clang-analyzer-core.uninitialized.Assign
* clang-analyzer-cplusplus.Move
* clang-analyzer-optin.cplusplus.VirtualCall
* modernize-loop-convert
* modernize-raw-string-literal
* modernize-use-equals-default
* modernize-use-override
* modernize-use-using
* performance-avoid-endl
* performance-inefficient-string-concatenation
* performance-inefficient-vector-operation
* performance-noexcept-move-constructor
* performance-unnecessary-value-param (and improve generator example)
* readability-duplicate-include
* readability-inconsistent-declaration-parameter-name
* readability-non-const-parameter
* readability-redundant-casting
* readability-redundant-member-init
* readability-redundant-smartptr-get
* readability-static-accessed-through-instance
* unused variable in amalgamted tests

Closes #2744

The license file was renamed with 6a502cc2f5fedd59b3495b58708f0d6d987ed9e1

* Apply PR #2297 to devel branch

It turns out that Issue #2272 partially affected the devel branch. When
building tests with C++20, the compiler emits a warning that top-level
comma expressions in array subscripts are depricated. Warnings are
treated as errors, so this caused the build to fail.

This commit adds localized warning suppression
in accordance with this recommendation here:
https://github.com/catchorg/Catch2/pull/2297#discussion_r720848392

Signed-off-by: Alecto Irene Perez <perez.cs@pm.me>

* Fixed unknown pragma warning on old versions of gcc & clang

This commit fixes an unkwown pragma warning on older versions of GCC
and Clang. These older versions don't have a warning for depricated use
of the comma subscript. Because warning suppression is localized, and
only refers to the comma subscript warning, it doesn't affect compiler
warnings in other parts of the code.

Signed-off-by: Alecto Irene Perez <perez.cs@pm.me>

* More #warning backwards compatibility fixes

Signed-off-by: Alecto Irene Perez <perez.cs@pm.me>