Incorrect XProfile data cache group

[johnjamesjacoby]

In the XProfile component, field data is currently grouped by user ID like: bp_xprofile_data_1

This has the unintended consequence of XProfile field data cannot be fully purged for all users without first analyzing which groups exist and unsetting them. This isn't necessarily wrong (because we are free to key and group things however we see fit) but it is the only cache group in all of WordPress & BuddyPress that currently works like this, and we may need to use dynamic cache groups in a more creative way in the future.

[johnjamesjacoby]

In ​6100.patch I'm switching the cache group over to bp_xprofile_data and setting it as a global group, then keying by $user_id:$field_id instead of just $field_id. I'm also taking advantage of BP_Component enhancements introduced in #5733. Patch also includes updated unit tests, props r-a-y.

[johnjamesjacoby]

In 9336:

XProfile data cache group updates:

• Switches from dynamic cache group to unique key for $user_id:$field_id.
• Introduces bp_xprofile_get_non_cached_field_ids() as a helper, based on bp_get_non_cached_field_ids().
• Registers bp_xprofile and bp_xprofile_data as global cache groups.
• Updates unit tests to pass with new cache keys.

Props r-a-y. Fixes #6100. See #5733.