Lint MXC APIs to centralise access

This adds linting rules to ensure that MXC APIs are only accessed via the
`Media` helper so they can be customised easily when desired.

Fixes https://github.com/vector-im/element-web/issues/16933

.eslintrc.js

@@ -54,7 +54,11 @@ module.exports = {
                 "error",
                 ...buildRestrictedPropertiesOptions(
                     ["window.innerHeight", "window.innerWidth", "window.visualViewport"],
-                    "Use UIStore to access window dimensions instead",
+                    "Use UIStore to access window dimensions instead.",
+                ),
+                ...buildRestrictedPropertiesOptions(
+                    ["*.mxcUrlToHttp", "*.getHttpUriForMxc"],
+                    "Use Media helper instead to centralise access for customisation.",
                 ),
             ],
         },
@@ -63,7 +67,10 @@ module.exports = {
 
 function buildRestrictedPropertiesOptions(properties, message) {
     return properties.map(prop => {
-        const [object, property] = prop.split(".");
+        let [object, property] = prop.split(".");
+        if (object === "*") {
+            object = undefined;
+        }
         return {
             object,
             property,