MM-30970 Add Basic unreadMentions support for collapsed threads (#16407)

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

store/storetest/thread_store.go

@@ -234,7 +234,7 @@ func testThreadStorePopulation(t *testing.T, ss store.Store) {
 	t.Run("Thread last updated is changed when channel is updated after UpdateLastViewedAtPost", func(t *testing.T) {
 		newPosts := makeSomePosts()
 
-		require.Nil(t, ss.Thread().CreateMembershipIfNeeded(newPosts[0].UserId, newPosts[0].Id, true))
+		require.Nil(t, ss.Thread().CreateMembershipIfNeeded(newPosts[0].UserId, newPosts[0].Id, true, false, true))
 		m, err1 := ss.Thread().GetMembershipForUser(newPosts[0].UserId, newPosts[0].Id)
 		require.Nil(t, err1)
 		m.LastUpdated -= 1000
@@ -254,7 +254,7 @@ func testThreadStorePopulation(t *testing.T, ss store.Store) {
 	t.Run("Thread last updated is changed when channel is updated after IncrementMentionCount", func(t *testing.T) {
 		newPosts := makeSomePosts()
 
-		require.Nil(t, ss.Thread().CreateMembershipIfNeeded(newPosts[0].UserId, newPosts[0].Id, true))
+		require.Nil(t, ss.Thread().CreateMembershipIfNeeded(newPosts[0].UserId, newPosts[0].Id, true, false, true))
 		m, err1 := ss.Thread().GetMembershipForUser(newPosts[0].UserId, newPosts[0].Id)
 		require.Nil(t, err1)
 		m.LastUpdated -= 1000
@@ -274,7 +274,7 @@ func testThreadStorePopulation(t *testing.T, ss store.Store) {
 	t.Run("Thread last updated is changed when channel is updated after UpdateLastViewedAt", func(t *testing.T) {
 		newPosts := makeSomePosts()
 
-		require.Nil(t, ss.Thread().CreateMembershipIfNeeded(newPosts[0].UserId, newPosts[0].Id, true))
+		require.Nil(t, ss.Thread().CreateMembershipIfNeeded(newPosts[0].UserId, newPosts[0].Id, true, false, true))
 		m, err1 := ss.Thread().GetMembershipForUser(newPosts[0].UserId, newPosts[0].Id)
 		require.Nil(t, err1)
 		m.LastUpdated -= 1000
@@ -294,7 +294,7 @@ func testThreadStorePopulation(t *testing.T, ss store.Store) {
 	t.Run("Thread last updated is changed when channel is updated after UpdateLastViewedAtPost for mark unread", func(t *testing.T) {
 		newPosts := makeSomePosts()
 
-		require.Nil(t, ss.Thread().CreateMembershipIfNeeded(newPosts[0].UserId, newPosts[0].Id, true))
+		require.Nil(t, ss.Thread().CreateMembershipIfNeeded(newPosts[0].UserId, newPosts[0].Id, true, false, true))
 		m, err1 := ss.Thread().GetMembershipForUser(newPosts[0].UserId, newPosts[0].Id)
 		require.Nil(t, err1)
 		m.LastUpdated += 1000