Q4 2024 cycle work

[kimcoleman]

This is the branch we used to work on the Q4 cycle for this Add On. Here's a list of what was done:

• Improved UI Consistency: Initial styling updates aligned with PMPro v3.1 standards.
• Refactored Core Logic: Directory and profile templates now share unified logic for handling field display values using the core PMPro displayValue() method when possible.
• Deprecated pmpro_member_directory_fields filter: in favor of more streamlined field handling. From now on, there will be more simplified shortcode attributes to list the elements you want to show, in the order you want them to show, with or without a label. Example: [pmpro_member_directory layout="3col" elements="avatar;display_name;Membership,membership_name"]
• Structural Enhancements: Organized the plugin files for better maintainability.
• Coding Standards and Simplifications: Cleaned up whitespace and adopted WordPress Coding Standards (WPCS)., Eliminated unnecessary query data and redundant filters.
• Added Search Shortcode: People can now add the search form outside the directory or profile shortcode for better templating.
• Added User Field Group for “Directory and Profile Preferences”. For now, this is where the “Hide from” checkbox will be.
• Added better support the levels attribute on directory and on profile page: If we see a levels attribute, we now adjust what membership data we use for other attributes like membership_name or membership_startdate.