Invite users to existing rooms (#441)

Invite users to existing rooms

Scope:

- Allow inviting from the room detail screen and the member list
- Invite option is only shown if the user has the correct power level
- Search flow the same as creating a new room, allowing multi-select
- Existing room members/invitees are disabled with a custom caption
- Sending is asynchronous, an error dialog will appear wherever the
  user is if necessary

Closes #245

appnav/build.gradle.kts

@@ -56,6 +56,7 @@ dependencies {
     implementation(projects.tests.uitests)
     implementation(libs.coil)
 
+    implementation(projects.services.apperror.impl)
     implementation(projects.services.appnavstate.api)
 
     testImplementation(libs.test.junit)