telega-server: Handle \xfe0f as specified in the Unicode standard

[zevlg]

Telega Setup

OS: Ubuntu 20.04.1 LTS
Emacs: GNU Emacs 29.0.50 (build 2, x86_64-pc-linux-gnu, GTK+ Version 3.24.20, cairo version 1.16.0)
Telega: telega v0.8.2 (TDLib v1.8.0) (telega-server v0.7.13)

Current Behavior

When emoji with \xfe0f code at the end is used in the text that is not listed in the telega-server emojis spec, then it is displayed incorrectly by telega. However, unicode specifies that \xfe0f could be used to emphasize that preceding character should be treated as emoji.

Steps to Reproduce

1. Send "here is ☃\xfe0f" as message to Saved Messages
2. Expect that "here is ☃️" is displayed in the Saved Messages

Possible Solution

When doing emoji lookup and lookup fails at current character being \xfe0f, treat previous char + \xfe0f as emoji