Add user search for dm chats (#739)

* Add searchUsers in ClientProxy

* Add UserSearchProtocol

* Delete UserSearch file

* Add search

* Refine StartChatScreen

* Improve StartChatViewModel

* Add localizations

* Fix no result style

* Update localizations

* Add UTs

* Add UI tests

* Cleanup

* Refine tests

* Add changelog.d file

* Naming refactor

* Refactor ClientProxyProtocol api

* Fix typo

* Add mark

* Rename tests

* Update Dangerfile

* Improve UI test code

* Refactor search api

* Improve style

* Improve combine chain

* Add comment

* Improve StartChatScreen

* Improve updateState

* Add extension Published.Publisher

* Improve UI tests

* Remove Combine import

* Cleanup

* Remove “proxy” wording

* Delete extra extensions

* Refactor Publisher api

ElementX/Sources/UITests/UITestsScreenIdentifier.swift

@@ -48,6 +48,7 @@ enum UITestsScreenIdentifier: String {
     case roomMemberDetailsIgnoredUser
     case reportContent
     case startChat
+    case startChatWithSearchResults
 }
 
 extension UITestsScreenIdentifier: CustomStringConvertible {