Add KDoc to the single-interface feature API modules

Cover the last remaining interfaces across features/announcement, cachecleaner,
call, contentscanner, createroom, knockrequests, lockscreen, rolesandpermissions,
startchat, userprofile and viewfolder, with their members and parameters.

Grouped into one commit rather than eleven near-empty ones, per the AGENTS.md rule
about tiny commits.

This completes every features/* api module.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

features/createroom/api/src/main/kotlin/io/element/android/features/createroom/api/CreateRoomEntryPoint.kt

@@ -15,9 +15,21 @@ import io.element.android.libraries.architecture.FeatureEntryPoint
 import io.element.android.libraries.matrix.api.core.RoomId
 
 interface CreateRoomEntryPoint : FeatureEntryPoint {
+    /**
+     * Configures the create-room flow before it is started, since it serves rooms and spaces from the same screens.
+     */
     interface Builder {
+        /**
+         * @param isSpace true to create a space rather than a room.
+         */
         fun setIsSpace(isSpace: Boolean): Builder
+
+        /**
+         * @param parentSpaceId the space the new room should be added to once created.
+         */
         fun setParentSpace(parentSpaceId: RoomId): Builder
+
+        /** Builds the node with the options configured so far. */
         fun build(): Node
     }