Added filter to hide Membership Settings for Access Plans

[andrewlimaza]

• ENHANCEMENT: Added the filter llms_show_membership_settings_for_access_plans to allow developers and integrations to hide this option if they override the membership plans or prevent course editors from adjusting the membership setting for the plan.

This will help us hide this option for Paid Memberships Pro & LifterLMS in streamline mode - strangerstudios/paid-memberships-pro#3088

How has this been tested?

Tested with the following filter call and shows that the section is hidden.
add_filter( 'llms_show_membership_settings_for_access_plans', '__return_false' );

Screenshots

Types of changes

New feature - filter added.

Checklist:

• This PR requires and contains at least one changelog file.
• My code has been tested.
• My code passes all existing automated tests.
• My code follows the LifterLMS Coding & Documentation Standards.

[brianhogg]

We should add a changelog here, though for a new dev only filter I don't think it's strictly necessary.