MM-48614: saves priority for drafts (#21752)

* MM-48614: saves priority for drafts

Adds a new column in the drafts table, "priority".
This way we can save post's priority in the draft.

Fixes OmitConnectionId, which when you published a ws event for a user
was getting bypassed.

Fixes Get for drafts returns deleted ones as well, which is needed for
upsert.

* Adds test case for the OmitConnectionId

* Addresses review comments, removes DeleteAt

* Vets

* Adds missing translation

* Re-instates DeleteAt column

* Adds separate case to get draft including deleted

* Fixes Update Draft

* Empty

api4/drafts.go

@@ -120,7 +120,12 @@ func deleteDraft(c *Context, w http.ResponseWriter, r *http.Request) {
 	channelID := c.Params.ChannelId
 
 	draft, err := c.App.GetDraft(userID, channelID, rootID)
-	if err != nil || c.AppContext.Session().UserId != draft.UserId {
+	if err != nil {
+		c.Err = err
+		return
+	}
+
+	if c.AppContext.Session().UserId != draft.UserId {
 		c.SetPermissionError(model.PermissionDeletePost)
 		return
 	}