Also added tests for types that require ADL lookup for their
`begin` and `end`.

Fixes #2615

Co-authored-by: Garz4 <fancygarz4@gmail.com>
Co-authored-by: Martin Hořeňovský <martin.horenovsky@gmail.com>

* Add new SKIP macro for skipping tests at runtime

This adds a new `SKIP` macro for dynamically skipping tests at runtime.
The "skipped" status of a test case is treated as a first-class citizen,
like "succeeded" or "failed", and is reported with a new color on the
console.

* Don't show "skipped assertions" in console/compact reporters

Also extend skip tests to cover a few more use cases.

* Return exit code 4 if all test cases are skipped

* Use LightGrey for the skip colour

This isn't great, but is better than the deep blue that was borderline
invisible on dark backgrounds. The fix is to redo the colouring
a bit, including introducing light-blue that is actually visible.

* Add support for explicit skips in all reporters

* --allow-running-no-tests also allows all tests to be skipped

* Add docs for SKIP macro, deprecate IEventListener::skipTest

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

Instead of redoing the whole line where path was found, only the
directory part of the path is removed, instead of removing all
of the line before the path starts.

This results in slight change in how junit and sonarqube approvals
come out, and significant change in how TeamCity reporter approvals
come out. This latter difference is the reason for the change,
as now the lines with `testFailed` and `testIgnored` messages
are not completely butchered.

We start at version 2, with version 1 being taken up by the output
from Catch2 v2.