Parse new macro declarative expression

[GrayJack]

As reference:

1. Tracking issue: declarative macros 2.0 rust-lang/rust#39412
2. Macros by example 2.0 (macro!) rust-lang/rfcs#1584
3. https://github.com/rust-lang/rfcs/blob/master/text/1584-macros.md

[GrayJack]

One think that it will fix is namespaced macro calls as well, like path::to::macro::call!()

[Stargateur]

This make all color fail every time I write some_module::macro_name!(). I like to avoid import too many into my namespace.

[wetneb]

This syntax is supported in tree-sitter-rust-orchard, a fork of this grammar. It's available as the tree-sitter-rust-orchard Rust crate on crates.io. If you need it in other package repositories let me know :)

I'd be happy to submit a PR for this feature here if there is renewed interest in reviewing PRs from external contributors in this repo.