Add syntax highlighting for multiline array PHPDoc

[maicol07]

Example:

/**
 * @param array{
 *  a: int,
 *  b: int
 *  } $arr
 */
 function c(array $arr) {}

Should be highlighted like the one-line syntax:

/**
 * @param array{a: int,b: int} $arr
 */ 
 function c(array $arr) {}

[klesun]

Related: #132

It would indeed be nice, though I gave up as I did not manage to make it work with Language Injections ;c