Allow filtering wp_redirect

[BrianHenryIE]

Currently, if the wp_redirect filter is used and returns false (as it is designed to accommodate) the wp_redirect() function returns and exit is run anyway.

This PR implements the code pattern suggested in the wp_redirect() php docblock which does not exit if the function returns early with false. See: pluggable.php

It also changes from using wp_redirect() to wp_safe_redirect() – AIUI the preferred function for local redirects.

// Do not redirect when activating `sqlite-database-integration` plugin.
add_filter( 'wp_redirect', function( string $location, int $status ): string|bool {
	if( str_ends_with( $location, 'sqlite-integration' ) ) {
		return false;
	}
	return $location;
}, 10, 2);

Allows #49 to be handled by WP CLI itself.