api(json-rpc): force stickers to be sent as stickers (#4819)

This approach uses a param field to enable forcing the sticker
`viewtype`. The first commit has the memory-only flag implemented, but
this flag is not persistent through the database conversion needed for
draft/undraft. That's why `param` has to be used.

follow up to #4814 
fixes #4739

---------

Co-authored-by: Septias <scoreplayer2000@gmail.comclear>

src/param.rs

@@ -187,6 +187,9 @@ pub enum Param {
 
     /// For Webxdc Message Instances: timestamp of summary update.
     WebxdcSummaryTimestamp = b'Q',
+
+    /// For messages: Whether [crate::message::Viewtype::Sticker] should be forced.
+    ForceSticker = b'X',
 }
 
 /// An object for handling key=value parameter lists.