Build Regex from static string in a const way

[ValentinColin]

Describe your feature request

Regex are often hardcoded, so it would be nice to be able to build a Regex from a static str in a const context to avoid handling error that will never happens. The build step of the regex we be done a compile time and not at runtime.

Example with the crate http: http::header::HeaderValue::from_static(&'static str).

[BurntSushi]

• Idea: compile-time verification of the regular expressions #607
• Compile-time regex for smaller WASM binary size #913
• what is the status of compile-time regex support? #1076
• `const` Regex compilation #1012