Co-authored-by: Fædon Jóhannes Sinis <fs@treble.tech>

Co-authored-by: Martin Hořeňovský <martin.horenovsky@gmail.com>

Did this, because with 3.0.1, the files
- catch_xmlwriter.cpp
- catch_string_manip.hpp
- catch_test_case_info.hpp

were missing

This led to some obvious and some obscure compile errors when compiling
with g++ 13.2.0 (std c++17 or c++20)
One of these errors being "Elaborated-type-specifier for a scoped enum
must not use the ‘class’ keyword"

Since this is a rather bad experience and debugging it is
time-consuming, I suggest to simply boost the recommended version in the
snippet which is likely copied by new Catch2 users

Introducing a new DISCOVERY_MODE mode option, which provides greater
control over when catch_discover_tests perforsm test discovery.

It has two supported modes:
* POST_BUILD: The default behavior, which adds a POST_BUILD command
  to perform test discovery after the test has been built as was
  always done so far.

* PRE_TEST: New mode, which delays test discovery until test execution.
  The generated include file generates the appropriate CTest files at
  runtime and regenerates the CTest files when the executable is
  updated.
  This mode can be used in build-environments that don't allow for
  executing the linked binaries at build-time (like in a
  cross-compilation environment).

DISCOVERY_MODE can be controlled in two ways:
1. Setting the DISCOVERY_MODE when calling catch_discover_tests.

2. Setting the global CMAKE_CATCH_DISCOVER_TESTS_DISCOVERY_MODE prior
   to calling gtest_discover_tests.

Closes #2493

Closes #2326
Closes #2438