Add tool to easily discover and remove or override erratic "Update URI" for plugins

[tobifjellner]

WordPress 5.8 introduced the plugin header field "Update URI". The purpose and usage of this field is described in ​https://make.wordpress.org/core/2021/06/29/introducing-update-uri-plugin-header-in-wordpress-5-8/

Unfortunately, there are some plugins that by mistake (perhaps while experimenting) populated this field with some value that forces WordPress to stop checking for updates to this plugin.

It would be good if the "Plugin list" could clearly indicate if a plugin is blocked from wp-org automatic updates via a declaration of "Update URI".
Additionally, it could even offer to remove that declaration on behalf of the user (perhaps after first expanding a "Read more" that could explain the situation and the risk associated with incorrectly removing this declaration.)

I finally decided that this ticket would best sort under "Plugins", but other components could also contribute to handling this issue:

• Site Health could comment that "The following plugin/plugins are blocked from automatic updates due to "Update URI" header.
• Upgrade/Install could add a note "n plugins skipped due to Update URI being set".