Audit bbp_insert_forum(), bbp_insert_topic() and bbp_insert_reply() functions

[netweb]

The purpose of this ticket is to audit the wp_insert_post() wrapper functions bbp_insert_forum(), bbp_insert_topic(), bbp_insert_reply() and bbp_create_initial_content() for the post and post meta values created by each function.

[netweb]

In 5773:

Tests: Add post meta test assertions to test_bbp_create_initial_content(), see #2805

[johnjamesjacoby]

In 5775:

Inserts: When inserting a forum/topic/reply, immediately update the new object so hierarchy is refreshed.

This commit addresses the last active post ID being incorrect after inserting topics and replies to a forum, and fixes a failing test (in BBP_Tests_Core_Update::test_bbp_create_initial_content).

See #2805.

[netweb]

In 5776:

Topics: Pass correct array value post_author to bbp_update_topic() in bbp_insert_topic() added in r5775
See #2805

[netweb]

In 5779:

Tests: Adds forum, topic and reply insert function tests:

• test_bbp_insert_forum() for bbp_insert_forum()
• test_bbp_insert_topic() for bbp_insert_topic()
• test_bbp_insert_reply() for bbp_insert_reply()

Props netweb. Fixes #2805