Editor: Register core block styles in one place.
Register all core blocks in a new function called register_core_block_style_handles. This mirrors the function wp_default_styles where all core styles are registered in one place. This improves block registration performance, as it avoids expensive file lookups, like realpath in register_block_style_handle. The new function register_core_block_style_handles uses glob to get all css files in the blocks directory. This glob is cached in a transient to save lookups on subsequent requests. The function register_block_style_handle now checks to see if the style handle is already registered before trying to register it again.
Props mukesh27, westonruter, flixos90, joemcgill, spacedmonkey.
Fixes #58528.