feat(garuda-common-settings): add syntax highlighting for configs in micro

Add syntax highlighting for config files opened in Micro that don't directly call a shell.
* Add a syntax definition for `filetype: conf` in `syntax/conf.yaml` with some basic rules (for example, highlighting commented lines);
* Define `/etc/*` and `/home/*/.config/*` as conf filetype in `settings.json`, because they contain a lot of config files that don't end in ".conf" or ".cfg".

etc/skel/.config/micro/settings.json

@@ -1,4 +1,10 @@
 {
+    "/etc/*": {
+        "filetype": "conf"
+    },
+    "/home/*/.config/*": {
+        "filetype": "conf"
+    },
     "autosu": true,
     "colorscheme": "geany",
     "mkparents": true

etc/skel/.config/micro/syntax/conf.yaml

@@ -0,0 +1,18 @@
+filetype: conf
+
+detect:
+    filename: "(\\.(conf)$|\\.(cfg)$)"
+
+rules:
+    - constant.string:
+        start: "\""
+        end: "\""
+        skip: "\\\\."
+        rules:
+            - constant.specialChar: "\\\\."
+
+    - comment:
+        start: "#"
+        end: "$"
+        rules:
+            - todo: "(TODO|XXX|FIXME):?"