[memory linux] Properly unlink shared memory

shm_unlink(name) is the proper way to close a shared memory in linux.
Prior to this, xenia was creating and not cleaning up shared memory handle
which would accumulate in /dev/shm. shm_unlink is the proper way of doing
this.
Add filename to CloseFileMappingHandle signature.
Add simple test to open and close.

src/xenia/base/memory.h

@@ -101,7 +101,8 @@ typedef void* FileMappingHandle;
 FileMappingHandle CreateFileMappingHandle(const std::filesystem::path& path,
                                           size_t length, PageAccess access,
                                           bool commit);
-void CloseFileMappingHandle(FileMappingHandle handle);
+void CloseFileMappingHandle(FileMappingHandle handle,
+                            const std::filesystem::path& path);
 void* MapFileView(FileMappingHandle handle, void* base_address, size_t length,
                   PageAccess access, size_t file_offset);
 bool UnmapFileView(FileMappingHandle handle, void* base_address, size_t length);