Add a way to get the colophon back as a string, rather than echoing.

[georgestephanis]

This will remedy an issue where there can be fatal errors from nested output buffers with callbacks -- for example:

[01-Feb-2024 16:46:28 UTC] PHP Fatal error:  ob_start(): Cannot use output buffering in output buffering display handlers

As an added bonus, it lets us stop using output buffers in the shortcode version, and just ask for the string directly.

Alternate resolution to #25 -- enabling just calling the method directly, rather than filtering.

Changes proposed in this Pull Request

• Less output buffering. More joy.

[georgestephanis]

Can be invoked safely directly instead of via action via

if ( function_exists( 'team51_credits' ) ) {
	$link = team51_credits(
		array(
			'return' => true
		)
	);
}

[Ninodevo]

This will be useful, looks good! Only PHPCS fixes are required.

[mlaetitia]

@georgestephanis went ahead and fixed the pending linter issues . Also tested this on my test site and is working as expected. let me know if there's anything else i can do to move forward here :)