Add .http file syntax highlighting

[LucasWagler]

Add syntax highlighting for the .http file format used by tools like REST Client for VSCode, rest.nvim, httpYac, and PhpStorm.

queries + tree-sitter
rest.nvim has highlight queries here (GPLv3 license). The developer of rest.nvim also maintains a tree-sitter parser for .http (MIT license).

Examples
The clients seem to roughly follow IETF RFC 9110, which contains an example request here.
httpYac provides some request examples here.

[erasin]

#6450 The first commit has queries support http. If you want, make pr again.