Tests: Refactor tests with better names, etc.

The basic tests now run on Windows correctly without needing to manually
copy any files -- the executables are output in the same location as the
necessary DLLs. However, tests that require *.pyd files (all code in the
Mod subdirectory, basically) still do not work on Windows as the test
executables cannot find those files. This is a work in progress.

tests/src/Mod/MeshPart/App/CMakeLists.txt

@@ -1,4 +1,4 @@
-target_sources(MeshPart_tests_run PRIVATE
+add_executable(MeshPart_tests_run
         MeshPart.cpp
 )
 

tests/src/Mod/MeshPart/CMakeLists.txt

@@ -1,7 +1,7 @@
+add_subdirectory(App)
+
 target_link_libraries(MeshPart_tests_run
     gtest_main
     ${Google_Tests_LIBS}
     MeshPart
 )
-
-add_subdirectory(App)