feat: format message from telegram and upload attachments (#1924)

* feat: format message from telegram and download documents

* fix: remove bool in expression

* refactor: convert to markdown

* refactor: resolve remarks and add support new message types

* refactor: resolve remarks

* feat: add test for mime type

---------

Co-authored-by: Александр Тумайкин <AATumaykin@tsum.ru>

plugin/telegram/chat.go

@@ -1,9 +1,19 @@
 package telegram
 
+type ChatType string
+
+const (
+	Private    = "private"
+	Group      = "group"
+	SuperGroup = "supergroup"
+	Channel    = "channel"
+)
+
 type Chat struct {
-	ID        int    `json:"id"`
-	Title     string `json:"title"`
-	Type      string `json:"type"`
-	FirstName string `json:"first_name"`
-	LastName  string `json:"last_name"`
+	ID        int      `json:"id"`
+	Title     string   `json:"title"`      // Title for supergroups, channels and group chats
+	Type      ChatType `json:"type"`       // Type of chat, can be either “private”, “group”, “supergroup” or “channel”
+	FirstName string   `json:"first_name"` // FirstName of the other party in a private chat
+	LastName  string   `json:"last_name"`  // LastName of the other party in a private chat
+	UserName  string   `json:"username"`   // UserName for private chats, supergroups and channels if available
 }