Introduce four CMake options to enable/disabled test variants or test frameworks

By default all four test variants (Catch2 vs. GTest and Approval vs. Unit) are enabled.

cpp/test/cpp_texttest/CMakeLists.txt

@@ -4,9 +4,9 @@ target_sources(${TEST_NAME} PRIVATE GildedRoseTextTests.cc)
 target_link_libraries(${TEST_NAME} GildedRoseLib)
 set_property(TARGET ${TEST_NAME} PROPERTY CXX_STANDARD 11)
 add_test(
-    NAME ${TEST_NAME}
-    COMMAND ${TEST_NAME}
-    WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
+  NAME ${TEST_NAME}
+  COMMAND ${TEST_NAME}
+  WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
 )
 
 # Set compiler option /FC for Visual Studio to to make the __FILE__ macro expand to full path.
@@ -15,5 +15,5 @@ add_test(
 # * https://docs.microsoft.com/en-us/cpp/preprocessor/predefined-macros?view=vs-2019
 # * https://docs.microsoft.com/en-us/cpp/build/reference/fc-full-path-of-source-code-file-in-diagnostics?view=vs-2019
 if (MSVC)
-    target_compile_options(${TEST_NAME} PRIVATE "/FC")
+  target_compile_options(${TEST_NAME} PRIVATE "/FC")
 endif()