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/userprofile/api/src/main/kotlin/io/element/android/features/userprofile/api/UserProfilePresenterFactory.kt

@@ -11,6 +11,12 @@ package io.element.android.features.userprofile.api
 import io.element.android.libraries.architecture.Presenter
 import io.element.android.libraries.matrix.api.core.UserId
 
+/**
+ * Creates the user profile presenter, so that other features can show a profile without depending on this one's implementation.
+ */
 fun interface UserProfilePresenterFactory {
+    /**
+     * @param userId the user whose profile is shown.
+     */
     fun create(userId: UserId): Presenter<UserProfileState>
 }