Allow `int` type for version in `_WP_Dependency` chain

[jeremyfelt]

_WP_Dependency()->ver, WP_Dependencies()->add(), wp_enqueue_style(), wp_register_style(), wp_enqueue_script(), and wp_register_script() all have a dependency's version type set as string|bool|null.

A common pattern for providing a script or style's version number is to use filemtime(), which returns an int. This can then be flagged by phpstan during static analysis as incorrect.

Because this is a valid way to generate a version number, and there is no part of the implementation that prevents the output of the number as a string, we should update these to support string|bool|int|null.

Trac ticket: https://core.trac.wordpress.org/ticket/63563

• Updated the function doc, to add support for int type on WP_Dependency, WP_Dependencies classes and wp_enqueue_script, wp_enqueue_style, wp_register_script, wp_register_style function.