xProfile: add extra arguments to `xprofile_data_value_before_save` and `xprofile_filtered_data_value_before_save` filters.

This allows plugin developers greater control over filtering profile data in specific circumstances, particularly for custom field types.

Fixes #5742, props needle.

git-svn-id: https://buddypress.svn.wordpress.org/trunk@8665 cdf35c40-ae34-48e0-9cc9-0c9da1808c22