Btest

* Always print a sorted list of failed tests to the state file.
(Benjamin Bannier, Corelight)

* Documentation updates. (Christian Kreibich, Corelight)

- Add a section on running btest, to give some basic context.
- Add more detail on btest invocation and test selection.
- Update docs for download and installation, shifting focus to PyPI.
- Move TEST-START-NEXT description to its section.

* Alternatives: Update `baselinedir` default after potentially
changing testbase. (Arne Welzel, Corelight)

* Fix issue where global configuration object wasn't updated for
environment variables taken from alternatives. (Arne Welzel,
Corelight)

* Ignore environment variable when overridden by alternative. (Arne
Welzel, Corelight)

* Preserve CRLF line-terminators in test files (Jon Siwek, Corelight)

Since the test itself may depend on their existence.

Related to https://github.com/zeek/zeek/issues/1497

* Support BTest installation via CMake (Christian Kreibich, Corelight)

This copies the relevant files manually. Relying on setup.py is
feasible but requires careful separation of build and source
directories, so currently explicit file lists are easier to maintain.