WP Admin bar: Update "About" links to helphub and support forums

[audrasjb]

In WP Admin Bar "About" section, we have two links that need to be updated:

Documentation

We should replace https://codex.wordpress.org/ with https://wordpress.org/support/.

Support

We should replace https://wordpress.org/support/ with https://wordpress.org/support/forums/.

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Related: #47239, #46790.

[audrasjb]

Help/About: Update WP Admin Bar links to Forums/HelpHub

[SergeyBiryukov]

In 50015:

Toolbar: Update Documentation and Support links.

This replaces the Codex URL in the "WordPress" section of the admin bar with the HelpHub URL, and updates the Support link to point to the forums.

Follow-up to [45140], [45412].

Props audrasjb.
Fixes #52352. See #46790, #47239.