Covered Theme module with tests

- Extracted `ColorReplacementGenerator`;
- Extracted `ColorConverterImpl`;
- Added documentation to some classes;
- `hex_to_rgba` now supports shorthand hex colors (#fff).

scripts/utils/theme/theme_preparation.py

@@ -1,5 +1,4 @@
 import os
-import warnings
 
 from scripts.utils import replace_keywords
 from scripts.utils.theme.theme_temp_manager import ThemeTempManager
@@ -45,11 +44,10 @@ class ThemePreparation:
         """
         Extract theme from source folder and prepare it for installation.
         """
-        self.file_manager.prepare_files(self.sources_location)
+        self.file_manager.copy_to_temp(self.sources_location)
         self.style_manager.generate_combined_styles(self.sources_location, self.temp_folder)
         self.file_manager.cleanup()
 
-    @warnings.deprecated
     def replace_filled_keywords(self):
         """
         Replace keywords in the theme files for filled mode.
@@ -62,4 +60,4 @@ class ThemePreparation:
                              ("BUTTON_ACTIVE", "ACCENT-FILLED_ACTIVE"),
                              ("BUTTON_INSENSITIVE", "ACCENT-FILLED_INSENSITIVE"),
                              ("BUTTON-TEXT-COLOR", "TEXT-BLACK-COLOR"),
-                             ("BUTTON-TEXT_SECONDARY", "TEXT-BLACK_SECONDARY"))
+                             ("BUTTON-TEXT_SECONDARY", "TEXT-BLACK_SECONDARY"))