Integrate tests into a “make test” target

[jcorporation]

Discussed in #1022

^{Originally posted by comburent May 12, 2023}
Hi,

Would you consider using CMake's CTest module in order to have the standard make test target from the default CMakeLists.txt?
These automated tests are useful for distributions where package testing is considered a part of the build process and helps spotting issues before the updates are sent.

[jcorporation]

• Set MYMPD_BUILD_TESTING=ON
• Build as normal
• Run make test