Remove JoinRule.Private from the codebase (#6129)

It shouldn't be in use, since it was never properly defined:

- The `Private` values coming from the SDK are considered to be `Invite` instead.
- Remove any existing `JoinRule.Private` usages in our code.

features/space/impl/src/main/kotlin/io/element/android/features/space/impl/leave/LeaveSpaceStateProvider.kt

@@ -38,7 +38,7 @@ class LeaveSpaceStateProvider : PreviewParameterProvider<LeaveSpaceState> {
                         ),
                         aSelectableSpaceRoom(
                             spaceRoom = aSpaceRoom(
-                                joinRule = JoinRule.Private,
+                                joinRule = JoinRule.Invite,
                             ),
                             isSelected = false,
                         ),
@@ -56,7 +56,7 @@ class LeaveSpaceStateProvider : PreviewParameterProvider<LeaveSpaceState> {
                         ),
                         aSelectableSpaceRoom(
                             spaceRoom = aSpaceRoom(
-                                joinRule = JoinRule.Private,
+                                joinRule = JoinRule.Invite,
                             ),
                             isSelected = true,
                         ),

features/space/impl/src/main/kotlin/io/element/android/features/space/impl/leave/LeaveSpaceView.kt

@@ -311,8 +311,8 @@ private fun SpaceItem(
             Row(
                 verticalAlignment = Alignment.CenterVertically,
             ) {
-                if (room.joinRule == JoinRule.Private) {
-                    // Picto for private
+                if (room.joinRule == JoinRule.Invite) {
+                    // Picto for invite only
                     Icon(
                         modifier = Modifier
                             .size(16.dp)