Bug#949401: ITP: tl-expected -- std::expected with functional-style extensions

[Nicholas Guriev <guriev-ns@ya.ru>]

Package: wnpp
Severity: wishlist
Owner: Nicholas Guriev <guriev-ns@ya.ru>

* Package name    : tl-expected
  Upstream Author : Simon Brand <simonrbrand@gmail.com>
* URL             : https://tl.tartanllama.xyz/, https://github.com/TartanLlama/expected
* License         : CC0 (Public Domain)
  Programming Lang: C++
  Description     : std::expected with functional-style extensions

Single header implementation of std::expected with functional-style
extensions. This is a new dependency of the upcoming Telegram Desktop
v1.9.4.