Create a unit_test macro

[furtib]

Why:
We want to integrate our tests into Bazel.

What:

• Added a Python script that checks whether specified patterns are available inside a file or a list of files.
• Added a Bazel macro for creating a test using said Python file.
• Updated template test
• Updated test documentation

Addresses:
#210

Notes:
In very old Bazel versions (older than 6.4.0), bazel test ... must get the flag: --experimental_cc_implementation_deps.

[nettle]

I like the idea!
However I would consider not mixing python tests and bazel tests.
But as a prototype it is definitely good!
And, as @Szelethus mentioned, we need a strategy for bazel tests.
And... please dont touch legacy tests - I need them as the reference!

[furtib]

However I would consider not mixing python tests and bazel tests.

I'm completely lost as to what this means.

[furtib]

I have left this patch alone for a long time 😅.

So I realized that almost every unit test (except cache tests) is convertable to this format.
I'm still not sure about what you meant under "not mixing python tests and bazel tests", but hopefully I have fixed it?

[Szelethus]

I don't think the PR name is very descriptive right now, because it adds a new macro, and demonstrates the usage on the virtual include tests.

I hate to be that guy (twice in one day), but can we fragment this just a little bit more? Can you at least put the test rewrite demo to a separate PR?

I like the overall direction, btw. Lets make sure we discuss with @nettle to avoid sinking too much effort into an idea that won't make the cut.

[nettle]

In general I like the idea :)

[Szelethus]

LGTM