Waiting on tree-sitter/tree-sitter-rust#164

It got rejected, unfortunately. So we need to wait for semantic tokens to be implemented: #5589

I like amaanq's take about this: tree-sitter/tree-sitter-rust#164 (comment). There's really no need for it to be built into tree-sitter-rust. It can be done with a separate very small grammar that parses Rust format strings that we can inject into any macro call who's first argument is a string.

We could go one step further and whitelist macrso which are known to accept format specifiers. That would mean it won't work for custom macros that call format_args! internally but I am fine with that (false negatives > false positives). They tend to be rather rare and we can likely cover almost all cases by adding macros from popular crates like defmt