Add roles and permissions screen (#2505)

The screen hasn't been added to the flows yet.

UnitTests/Sources/RoomRolesAndPermissionsScreenViewModelTests.swift

@@ -0,0 +1,40 @@
+//
+// Copyright 2022 New Vector Ltd
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+import XCTest
+
+@testable import ElementX
+
+@MainActor
+class RoomRolesAndPermissionsScreenViewModelTests: XCTestCase {
+    var viewModel: RoomRolesAndPermissionsScreenViewModelProtocol!
+    
+    var context: RoomRolesAndPermissionsScreenViewModelType.Context {
+        viewModel.context
+    }
+
+    func testEmptyCounters() {
+        viewModel = RoomRolesAndPermissionsScreenViewModel(roomProxy: RoomProxyMock(with: .init()))
+        XCTAssertEqual(context.viewState.administratorCount, 0)
+        XCTAssertEqual(context.viewState.moderatorCount, 0)
+    }
+
+    func testFilledCounters() async throws {
+        viewModel = RoomRolesAndPermissionsScreenViewModel(roomProxy: RoomProxyMock(with: .init(members: .allMembersAsAdmin)))
+        XCTAssertEqual(context.viewState.administratorCount, 2)
+        XCTAssertEqual(context.viewState.moderatorCount, 1)
+    }
+}