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

features/createroom/impl/src/main/kotlin/io/element/android/features/createroom/impl/addpeople/AddPeopleView.kt

@@ -33,6 +33,7 @@ import androidx.compose.ui.unit.dp
 import androidx.compose.ui.unit.sp
 import io.element.android.features.createroom.impl.R
 import io.element.android.features.createroom.impl.components.UserListView
+import io.element.android.features.createroom.impl.userlist.UserListEvents
 import io.element.android.features.createroom.impl.userlist.UserListState
 import io.element.android.libraries.designsystem.components.button.BackButton
 import io.element.android.libraries.designsystem.preview.ElementPreviewDark
@@ -54,13 +55,17 @@ fun AddPeopleView(
     Scaffold(
         modifier = modifier,
         topBar = {
-            if (!state.isSearchActive) {
-                AddPeopleViewTopBar(
-                    hasSelectedUsers = state.selectedUsers.isNotEmpty(),
-                    onBackPressed = onBackPressed,
-                    onNextPressed = onNextPressed,
-                )
-            }
+            AddPeopleViewTopBar(
+                hasSelectedUsers = state.selectedUsers.isNotEmpty(),
+                onBackPressed = {
+                    if (state.isSearchActive) {
+                        state.eventSink(UserListEvents.OnSearchActiveChanged(false))
+                    } else {
+                        onBackPressed()
+                    }
+                },
+                onNextPressed = onNextPressed,
+            )
         }
     ) { padding ->
         Column(
@@ -73,6 +78,7 @@ fun AddPeopleView(
                 modifier = Modifier
                     .fillMaxWidth(),
                 state = state,
+                showBackButton = false,
             )
         }
     }

features/createroom/impl/src/main/kotlin/io/element/android/features/createroom/impl/components/SearchUserBar.kt

@@ -39,6 +39,7 @@ fun SearchUserBar(
     active: Boolean,
     isMultiSelectionEnabled: Boolean,
     modifier: Modifier = Modifier,
+    showBackButton: Boolean = true,
     placeHolderTitle: String = stringResource(R.string.common_search_for_someone),
     onActiveChanged: (Boolean) -> Unit = {},
     onTextChanged: (String) -> Unit = {},
@@ -52,6 +53,7 @@ fun SearchUserBar(
         onActiveChange = onActiveChanged,
         modifier = modifier,
         placeHolderTitle = placeHolderTitle,
+        showBackButton = showBackButton,
         contentPrefix = {
             if (isMultiSelectionEnabled && active && selectedUsers.isNotEmpty()) {
                 SelectedUsersList(

features/createroom/impl/src/main/kotlin/io/element/android/features/createroom/impl/components/UserListView.kt

@@ -36,6 +36,7 @@ import io.element.android.libraries.matrix.ui.components.SelectedUsersList
 fun UserListView(
     state: UserListState,
     modifier: Modifier = Modifier,
+    showBackButton: Boolean = true,
     onUserSelected: (MatrixUser) -> Unit = {},
     onUserDeselected: (MatrixUser) -> Unit = {},
 ) {
@@ -49,6 +50,7 @@ fun UserListView(
             selectedUsers = state.selectedUsers,
             active = state.isSearchActive,
             isMultiSelectionEnabled = state.isMultiSelectionEnabled,
+            showBackButton = showBackButton,
             onActiveChanged = { state.eventSink(UserListEvents.OnSearchActiveChanged(it)) },
             onTextChanged = { state.eventSink(UserListEvents.UpdateSearchQuery(it)) },
             onUserSelected = {