Add Proc macro server

[Draggu]

Stack:

• Add ExpandInline handler #1686
• Add ExpandDerive handler #1685
• Add ExpandAttribute handler #1684
• Add DefinedMacros handler #1683
• Add request handling #1682
• Add Proc macro server #1681 ⬅
• Proc macro server: Load ProcMacroHost #1680
• Add proc-macro-server command #1679
• Proc macro server API #1678
• cairo-lang-macro fix null-byte panics #1677
• Add derives to cairo-lang-macro #1676

⚠️ Part of a stack created by spr. Do not merge manually using the UI - doing so may have unexpected results.

[mkaput]

a lot of vertical noise here imo

Suggested change

	if stdin.read_line(&mut line).is_err() {
	eprintln!("Error occurred while reading from stdin");
	break;
	}
	if line.is_empty() {
	continue;
	}
	let Ok(request) = serde_json::from_str(&line) else {
	eprintln!("Error occurred while deserializing request, used input:\n{line}");
	break;
	};
	if reader_sender.send(request).is_err() {
	eprintln!("Error occurred while sending request to worker threads");
	break;
	}
	if stdin.read_line(&mut line).is_err() {
	eprintln!("Error occurred while reading from stdin");
	break;
	}
	if line.is_empty() {
	continue;
	}
	let Ok(request) = serde_json::from_str(&line) else {
	eprintln!("Error occurred while deserializing request, used input:\n{line}");
	break;
	};
	if reader_sender.send(request).is_err() {
	eprintln!("Error occurred while sending request to worker threads");
	break;
	}

[mkaput]

1. don't you want to build errors here & use anyhow contexts?
2. you're logging to stderr here, so use tracing macros

[mkaput]

we don't use nested imports in our codebases