docs: create a Sphinx domain extension to document preference settings

.gitignore

@@ -123,6 +123,5 @@ phoebus-product/settings_template.ini
 
 # doc files generated by docs/source/conf.py 
 docs/source/applications.rst
-docs/source/preference_properties.rst
 docs/source/services.rst
 

docs/source/_ext/preferences_listing/__init__.py

@@ -0,0 +1,37 @@
+"""Extension that creates a new Sphinx domain for documenting Phoebus' preference settings.
+
+Sphinx domain: https://www.sphinx-doc.org/en/master/usage/domains/index.html
+Creating a Sphinx domain tutorial: https://www.sphinx-doc.org/en/master/development/tutorials/adding_domain.html
+"""
+
+from pathlib import Path
+
+from sphinx.application import Sphinx
+from sphinx.util.typing import ExtensionMetadata
+
+from ._domain import PreferencesDomain
+from ._parsing import parse_all_properties_files
+
+
+def setup(app: Sphinx) -> ExtensionMetadata:
+    app.add_config_value(
+        "phoebus_root",
+        (Path(app.confdir) / "../..").resolve(),
+        "html",
+        Path,
+    )
+    app.add_config_value(
+        "phoebus_repository",
+        "https://github.com/ControlSystemStudio/phoebus",
+        "html",
+        str,
+    )
+
+    app.add_domain(PreferencesDomain)
+    app.connect("config-inited", parse_all_properties_files)
+
+    return {
+        "version": "0.1",
+        "parallel_read_safe": True,
+        "parallel_write_safe": True,
+    }