Review filter priority

[Jon007]

The following filter priority was set for compatibility with Ultimate Member:
add_filter( 'get_avatar', [ $avatar, 'filter_avatar' ], 199999, 6 );

However in another project I reduced priority for compatibility with Super Socializer in order to create a priority like:

1. Use user uploaded picture if available (Basic User Avatars works fine for this even if not updated for 2 years)
2. Use social media avatar if available
3. [User Badge if awarded, via custom theme]
4. Cat

This is just a note that in an ideal world or when time available, there would be a more standard way of managing the prioritization etc.