To make this all work, I had to remove the stringification cache
from matchers. In theory, this can cause performance penalty in
cases where single matcher instance is stringified multiple times,
but in practice this does not happen much, and the difference is
surprisingly small anyway, because the performance of stringification
is already horrible and full of allocating strings just to throw
them away.
The matcher combinators need P2738 from C++26 to be `constexpr`.
Closes#3091
This PR primarily accomplishes two tasks:
1) It adds MODULE.bazel.lock to the .gitignore file.
2) It includes a Bazel build rule for SelfTest, which can be utilized with the command bazel test //tests:catch2_self_test.