Refactor GDM module to correspond SOLID principles

- I don't know how I will support this hell ahh code;
- Added some methods to gnome_shell_theme_builder.py;
- Added "color" property "install" method from theme_base.py.

scripts/utils/global_theme/gdm.py

@@ -0,0 +1,88 @@
+from scripts.types.theme_base import ThemeBase
+from scripts.utils.global_theme.gdm_installer import GDMThemeInstaller
+from scripts.utils.global_theme.gdm_preparer import GDMThemePreparer
+from scripts.utils.global_theme.gdm_remover import GDMThemeRemover
+from scripts.utils.global_theme.gdm_theme_prepare import GDMThemePrepare
+
+
+class GDMTheme(ThemeBase):
+    """
+    GDM theming module.
+
+    This module provides functionality to prepare, install, and remove GNOME Display Manager themes.
+    It follows a workflow of:
+    1. Preparing themes from existing GDM resources
+    2. Installing themes with custom colors/styles
+    3. Providing ability to restore original GDM themes
+
+    The main entry point is the GDMTheme class, which orchestrates the entire theme management process.
+    """
+    def __init__(self, preparer: GDMThemePreparer, installer: GDMThemeInstaller, remover: GDMThemeRemover):
+        """
+        :param preparer: GDMThemePreparer instance for preparing themes
+        :param installer: GDMThemeInstaller instance for installing themes
+        :param remover: GDMThemeRemover instance for removing themes
+        """
+        self.preparer = preparer
+        self.installer = installer
+        self.remover = remover
+
+        self.themes: list[GDMThemePrepare] = []
+
+    def prepare(self):
+        """
+        Prepare the theme for installation.
+
+        This method:
+        1. Checks if a theme is already installed and uses backup if needed
+        2. Extracts relevant theme files
+        3. Processes them into ready-to-compile GDMThemePrepare objects
+
+        The processed themes are stored in the themes attribute for later use.
+        """
+        if self._is_installed():
+            self.preparer.use_backup_as_source()
+        self.themes = self.preparer.prepare()
+
+    def _is_installed(self) -> bool:
+        """
+        Check if a GDM theme is currently installed.
+
+        This looks for specific markers in the system gresource files
+        that indicate our theme has been installed.
+
+        :return: True if a custom theme is installed, False otherwise
+        """
+        return self.installer.is_installed()
+
+    def install(self, hue: int, name: str, sat: float | None = None):
+        """
+        Install the prepared theme with specified color adjustments.
+
+        This method:
+        1. Compiles theme files with the specified hue and saturation
+        2. Creates a backup of the original GDM theme if one doesn't exist
+        3. Installs the compiled theme to the system
+
+        :param hue: The hue adjustment (0-360) to apply to the theme
+        :param name: The name of the theme to be installed. In GDM will only be shown in logger
+        :param sat: Optional saturation adjustment (0-100) to apply
+        """
+        self.installer.compile(self.themes, hue, name, sat)
+
+        if not self._is_installed():
+            self.installer.backup()
+
+        self.installer.install()
+
+    def remove(self):
+        """
+        Remove the installed theme and restore the original GDM theme.
+
+        If no theme is installed, displays a warning message to the user.
+        This will restore from backup and update GDM alternatives if needed.
+        """
+        if self._is_installed():
+            self.remover.remove()
+        else:
+            self.remover.warn_not_installed()