This avoids the need to explicitly specify the flags and the character set. WordPress will use predefined flags and detect the character set used by the site.
Prompted by #597
By default, these buttons are generated using the get_submit_button() API function, but that function is only available in the admin dashboard (unless explicitly loaded). Previously, the buttons were not shown in the front end.
This patch adds a fallback that generates the buttons directly. These won't look exactly the same as admin buttons due to admin styles not being loaded, and WP may change submit button HTML at some point, but the fallback buttons should still work.
Fixes#568
Previously, triggerUpdateCheckOnce() was attached to a transient filter, but that's no longer the case. Now it's passed directly to WP_CLI::add_hook().
However, it still takes and returns a value. WP-CLI documentation says that the `before_invoke:<command>` hook takes one argument and acts as a filter.
PUC already used `upgrader_process_complete` to remove hooks when the plugin version it was part of was deleted during an update. However, that did not catch more obscure situations, such as apparently being called from an unrelated AJAX request while the host plugin version was being deleted (a user sent a stack trace where it seems that was what happened).
When a plugin update overwrites PUC with a different version of PUC, the hook callbacks registered by the old version can trigger fatal errors when they try to autoload now-deleted PHP files. Normally, PUC avoids this by using an `upgrader_process_complete` hook to check if one of its files still exists, and removing the hooks if the file is missing.
However, it appears that WP Last Modified Info has its own `upgrader_process_complete` callback that runs earlier. That callback tries to download plugin metadata, which indirectly triggers some PUC hooks, and leads to the fatal error(s) mentioned earlier.
Fixed by extracting the relevant part of `upgraderProcessComplete` to a separate method and registering that method as a callback for the same hook, but with an earlier priority (1 instead of 11). It appears that WP Last Modified Info uses the default priority: 10.
This can happen when PUC is configured to use a branch (as opposed to tags or releases) and it fails to retrieve the main plugin file from the repository, e.g. due to API rate limits. Then it can't get the "Version" header from the main plugin file.
See #526
Update metadata can include additional, arbitrary fields such as request statistics, licence information, and so on. This data was stored as dynamic properties on Metadata subclasses, which triggered a deprecation notice in PHP 8.2. Fixed by explicitly storing dynamic fields in a new protected property and adding magic methods to access/modify those fields.
Fixes#536
