OSF: Used model.NewPointer everywhere (#27838)

```release-note
NONE
```

server/platform/services/sharedchannel/channelinvite.go

@@ -276,7 +276,7 @@ func (scs *Service) handleChannelCreation(invite channelInviteMsg, rc *model.Rem
 		Header:      invite.Header,
 		Purpose:     invite.Purpose,
 		CreatorId:   rc.CreatorId,
-		Shared:      model.NewBool(true),
+		Shared:      model.NewPointer(true),
 	}
 
 	// check user perms?

server/platform/services/sharedchannel/channelinvite_test.go

@@ -93,8 +93,8 @@ func TestOnReceiveChannelInvite(t *testing.T) {
 		createPostPermission := model.ChannelModeratedPermissionsMap[model.PermissionCreatePost.Id]
 		createReactionPermission := model.ChannelModeratedPermissionsMap[model.PermissionAddReaction.Id]
 		updateMap := model.ChannelModeratedRolesPatch{
-			Guests:  model.NewBool(false),
-			Members: model.NewBool(false),
+			Guests:  model.NewPointer(false),
+			Members: model.NewPointer(false),
 		}
 
 		mockApp.On("CreateChannelWithUser", mockTypeReqContext, mockTypeChannel, mockTypeString).Return(channel, nil)
@@ -175,7 +175,7 @@ func TestOnReceiveChannelInvite(t *testing.T) {
 			{"two remotes", &model.User{Id: model.NewId(), RemoteId: &testRemoteID}, &model.User{Id: model.NewId(), RemoteId: &testRemoteID}, true, false},
 			{"two locals", &model.User{Id: model.NewId()}, &model.User{Id: model.NewId()}, true, false},
 			{"can't see", &model.User{Id: model.NewId(), RemoteId: &testRemoteID}, &model.User{Id: model.NewId()}, false, false},
-			{"invalid remoteid", &model.User{Id: model.NewId(), RemoteId: model.NewString("bogus")}, &model.User{Id: model.NewId()}, true, false},
+			{"invalid remoteid", &model.User{Id: model.NewId(), RemoteId: model.NewPointer("bogus")}, &model.User{Id: model.NewId()}, true, false},
 		}
 
 		for _, tc := range testCases {

server/platform/services/sharedchannel/service.go

@@ -220,8 +220,8 @@ func (scs *Service) makeChannelReadOnly(channel *model.Channel) *model.AppError
 	createPostPermission := model.ChannelModeratedPermissionsMap[model.PermissionCreatePost.Id]
 	createReactionPermission := model.ChannelModeratedPermissionsMap[model.PermissionAddReaction.Id]
 	updateMap := model.ChannelModeratedRolesPatch{
-		Guests:  model.NewBool(false),
-		Members: model.NewBool(false),
+		Guests:  model.NewPointer(false),
+		Members: model.NewPointer(false),
 	}
 
 	readonlyChannelModerations := []*model.ChannelModerationPatch{

server/platform/services/sharedchannel/sync_recv.go

@@ -194,7 +194,7 @@ func (scs *Service) upsertSyncUser(c request.CTX, user *model.User, channel *mod
 	var userSaved *model.User
 	if euser == nil {
 		// new user.  Make sure the remoteID is correct and insert the record
-		user.RemoteId = model.NewString(rc.RemoteId)
+		user.RemoteId = model.NewPointer(rc.RemoteId)
 		if userSaved, err = scs.insertSyncUser(c, user, channel, rc); err != nil {
 			return nil, err
 		}
@@ -353,7 +353,7 @@ func (scs *Service) updateSyncUser(rctx request.CTX, patch *model.UserPatch, use
 func (scs *Service) upsertSyncPost(post *model.Post, targetChannel *model.Channel, rc *model.RemoteCluster) (*model.Post, error) {
 	var appErr *model.AppError
 
-	post.RemoteId = model.NewString(rc.RemoteId)
+	post.RemoteId = model.NewPointer(rc.RemoteId)
 	rctx := request.EmptyContext(scs.server.Log())
 
 	rpost, err := scs.server.GetStore().Post().GetSingle(rctx, post.Id, true)
@@ -450,7 +450,7 @@ func (scs *Service) upsertSyncReaction(reaction *model.Reaction, targetChannel *
 		if user.GetRemoteID() != rc.RemoteId {
 			return nil, fmt.Errorf("reaction sync failed: %w", ErrRemoteIDMismatch)
 		}
-		reaction.RemoteId = model.NewString(rc.RemoteId)
+		reaction.RemoteId = model.NewPointer(rc.RemoteId)
 		savedReaction, appErr = scs.app.SaveReactionForPost(request.EmptyContext(scs.server.Log()), reaction)
 	} else {
 		// make sure the reaction being deleted is owned by the remote