tests: Add unit tests for the GPU range tracking buffer container

Due to how error prone the container design is, this commit adds unit
tests for it.

Some tests taken from here are based on bugs from using this buffer
container in games, so if we ever break it in the future in a way that
might harm games, the tests should fail.

src/tests/CMakeLists.txt

@@ -6,6 +6,7 @@ add_executable(tests
     common/ring_buffer.cpp
     core/core_timing.cpp
     tests.cpp
+    video_core/buffer_base.cpp
 )
 
 create_target_directory_groups(tests)