CMake: Support for XML documentation

Add new function generate_doc_source to python_callouts.cmake
Update Test extension to use generate_doc_source function and include generated file in the build.

Cleanup:
Fix godotcpp.py imports after rebase
Pre-Commit hook sorted python imports in doc_source_generator.py
- replace ${CMAKE_CURRENT_SOURCE_DIR} with ${godot-cpp_SOURCE_DIR} when referencing current working directory and script locations when invoking python scripts.

Co-authored-by: David Snopek <dsnopek@gmail.com>

test/CMakeLists.txt

@@ -3,11 +3,19 @@ Integration Testing
 -------------------
 
 The Test target used to validate changes in the GitHub CI.
-
 ]=======================================================================]
 
 message( STATUS "Testing Integration targets are enabled.")
 
+# Generate Doc Data
+file( GLOB_RECURSE DOC_XML
+    LIST_DIRECTORIES NO
+    CONFIGURE_DEPENDS
+    "${CMAKE_CURRENT_SOURCE_DIR}/doc_classes/*.xml" )
+
+set( DOC_DATA_SOURCE "${CMAKE_CURRENT_BINARY_DIR}/src/gen/doc_data.gen.cpp" )
+generate_doc_source( "${DOC_DATA_SOURCE}" "${DOC_XML}" )
+
 foreach( TARGET_ALIAS template_debug template_release editor )
     set( TARGET_NAME "godot-cpp.test.${TARGET_ALIAS}" )
     set( LINK_TARGET "godot-cpp::${TARGET_ALIAS}" )
@@ -23,6 +31,11 @@ foreach( TARGET_ALIAS template_debug template_release editor )
             src/tests.h
     )
 
+    # conditionally add doc data to compile output
+    if( TARGET_ALIAS MATCHES "editor|template_debug" )
+        target_sources( ${TARGET_NAME} PRIVATE "${DOC_DATA_SOURCE}" )
+    endif(   )
+
     target_link_libraries( ${TARGET_NAME} PRIVATE ${LINK_TARGET} )
 
     ### Get useful properties of the library