Using a file(GLOB) to find all the test files in a directory is an easy
hack to get things started, but has some drawbacks. Namely, if you add
a test, it won't be found again without re-running CMake. `ninja` seems
to do this automatically, but it would be nice to one day stop seeing it
rechecking our globbed directories.
This patch adds some rudimentary tests for InodeWatcher. It tests the
basic functionality, but maybe there are corner cases I haven't caught.
Additionally, this is our first LibCore test. :^)