Document the globals in various functions

[krunal265]

Comment on some functions that need to be improved. In the comment, need to mention the global variable that is used in the function.

Files:
1) wp-admin/includes/post.php

function name: the_block_editor_meta_boxes()

2) wp-includes/block-template-utils.php

function name: wp_generate_block_templates_export_file()

3) wp-includes/class-wp-oembed-controller.php

function name: get_proxy_item()

[krunal265]

Patch added

[SergeyBiryukov]

Thanks for the patch!

[SergeyBiryukov]

In 54831:

Docs: Document the usage of globals in some functions.

This affects:

• the_block_editor_meta_boxes()
• wp_generate_block_templates_export_file()
• WP_oEmbed_Controller::get_proxy_item()

Follow-up to [44131], [48135], [51151], [53129].

Props krunal265.
Fixes #57082.