feat: add no-sync-fn-in-async-fn rule

[sigmaSd]

fix #1177

[CLAassistant]

All committers have signed the CLA.

[sigmaSd]

[sigmaSd]

I add a suggestion for the async variant

[sigmaSd]

seems like there is a lot of code like this https://github.com/search?q=%2Fasync.*%5Cn.*Deno.*Sync%2F+language%3ATypeScript&type=code

[sigmaSd]

couple of notes

• this won't catch wrapped blocking function like function a() {Deno.readSync..} async function b() {a()}
• console.log is also blocking, there could be other functions ?
• rust issues Lint idea: find known-blocking constructs in async contexts rust-lang/rust-clippy#4377 Detect and prevent blocking functions in async code rust-lang/wg-async#19

[magurotuna]

It would be even better to also show valid examples with async functions containing async version of built-in functions, because we prefer async functions in general. Something like:

async function foo() {
  await Deno.readTextFile("");
}

[magurotuna]

LGTM. Thanks so much!