Support coloured Problem Matcher output

[stefanbuck]

Describe the enhancement

Wouldn't it be useful to be able to add colors to the Problem Matcher output using ANSI codes.

Additional information

Current

Suggested

[ockham]

Weird, according to the @actions/core package README, it seems like ANSI colors would be supported? That README refers to the core.info() function, but that is basically just an alias of process.stdout.write():

toolkit/packages/core/src/core.ts

Lines 165 to 171 in e76deca

	/**
	* Writes info to log with console.log.
	* @param message info message
	*/
	export function info(message: string): void {
	process.stdout.write(message + os.EOL)
	}

So one would think that doing the same thing manually should also work... 🤔

Edit: Disregard, upon closer reading, this issue is about Problem Matchers, rather than (generalized) annotations. Sorry for the noise!