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/joinroom/impl/src/main/kotlin/io/element/android/features/joinroom/impl/JoinRoomPresenter.kt

@@ -376,10 +376,9 @@ private fun JoinRule?.toJoinAuthorisationStatus(): JoinAuthorisationStatus {
     return when (this) {
         JoinRule.Knock,
         is JoinRule.KnockRestricted -> JoinAuthorisationStatus.CanKnock
-        JoinRule.Invite,
-        JoinRule.Private -> JoinAuthorisationStatus.NeedInvite
+        JoinRule.Invite -> JoinAuthorisationStatus.NeedInvite
         is JoinRule.Restricted -> JoinAuthorisationStatus.Restricted
         JoinRule.Public -> JoinAuthorisationStatus.CanJoin
-        else -> JoinAuthorisationStatus.Unknown
+        is JoinRule.Custom, null -> JoinAuthorisationStatus.Unknown
     }
 }

features/joinroom/impl/src/test/kotlin/io/element/android/features/joinroom/impl/JoinRoomPresenterTest.kt

@@ -1035,34 +1035,6 @@ class JoinRoomPresenterTest {
         }
     }
 
-    @Test
-    fun `present - when room is not known RoomPreview is loaded as Private`() = runTest {
-        val client = FakeMatrixClient(
-            getNotJoinedRoomResult = { _, _ ->
-                Result.success(
-                    aRoomPreview(
-                        info = aRoomPreviewInfo(joinRule = JoinRule.Private),
-                        roomMembershipDetails = {
-                            Result.success(aRoomMembershipDetails())
-                        },
-                    )
-                )
-            },
-            spaceService = FakeSpaceService(
-                spaceRoomListResult = { FakeSpaceRoomList() },
-            ),
-        )
-        val presenter = createJoinRoomPresenter(
-            matrixClient = client
-        )
-        presenter.test {
-            skipItems(1)
-            awaitItem().also { state ->
-                assertThat(state.joinAuthorisationStatus).isEqualTo(JoinAuthorisationStatus.NeedInvite)
-            }
-        }
-    }
-
     @Test
     fun `present - when room is not known RoomPreview is loaded as Custom`() = runTest {
         val client = FakeMatrixClient(