Edit Post: Update PluginBlockSettingsMenuItem to use block-editor class name

[aduth]

Previously: #14420, #14112

This pull request seeks to update a few remaining occurrences of class names which have since been updated from editor- to block-editor- prefix to align with the creation of a new block editor module in #14112.

Aside: This serves as good reaffirmation of why there exists guidelines around class naming specific to modules and in how violations become sources of issue for future maintenance.

Testing instructions:

Verify that custom plugin menu items and groups receive appropriate styles. I tested using the "TinyMCE Advanced" plugin, which includes a custom menu item for "Convert to Blocks".

Future Tasks:

These components should not be applying the class name in the way they are. The changes here are the most conservative resolution to the bug, but I would suggest one of the following future enhancements:

1. Eliminate the block-editor-block-settings-menu__control class name altogether. If it's assumed to be of type wp.components.MenuItem, then BlockSettingsMenu can simply target that class name (.components-menu-item__button) directly in its own styles.
2. Abstract components in block-editor which apply the necessary class names, to be used by edit-post and others.

[aduth]

Follow-up task: #14749