BP Rewrites: Optimize code to build URLs

[imath]

In #4954 the bp_members_get_path_chunks() & bp_groups_get_path_chunks() functions were introduced after the bp_rewrites_get_slug() one. These two functions are more convenient to use than building an associative array in which the bp_rewrites_get_slug() is used to make sure slugs are customized. They simply accept a regular array containing URL chunks. Let's use these two first functions more and bp_rewrites_get_slug() a lot less.

BP Rewrites: Optimizing code to build URLs

Use less the bp_rewrites_get_slug() function and more the bp_members_get_path_chunks() & bp_groups_get_path_chunks() ones

Trac ticket: ​https://buddypress.trac.wordpress.org/ticket/8923

[imath]

In 13503:

BP Rewrites: optimize the code used to build URLs

The bp_members_get_path_chunks() & bp_groups_get_path_chunks() functions are making sure URL chunks are customized according to the slugs settings. Instead of redoing at many places all or some of the operations performed by these functions, update the code to build URLs so that it uses these functions.

See #4954
Fixes #8923
Closes ​https://github.com/buddypress/buddypress/pull/117

[imath]

In 13619:

Improve inline doc for Members & Groups get_path_chunks() functions

• bp_members_get_path_chunks() & bp_groups_get_path_chunks(): clearly inform these functions goal is to return customized slugs.
• Add missing inline comment for the bp_groups_get_path_chunks() $context parameter.

See #8923