Apply BP REST API - V2 internally

[espellcaste]

This ticket is currently blocked by #9145

This is a placeholder ticket to keep track of places we need to use the V2 REST API internally. Here is a list of features or places where we will need to upgrade to use the V2 of the BP REST API.

• Ajax;
• BP Block;
• #9156;
• #8774;
• Manage Group Members UI.

[imath]

Just checked "Manage Group Members UI", it behaves as expected with BP REST API v2 ✅

Replace buddypress/v1 with buddypress/v2.

Trac ticket: ​https://buddypress.trac.wordpress.org/ticket/9229

[imath]

In 14033:

BP Blocks: update hardcoded endpoints to use BP REST API v2

See #9229
Closes ​https://github.com/buddypress/buddypress/pull/378

[espellcaste]

In 14069:

Messages: filter threads by recipient IDs.

bp_has_message_threads (and the BP REST API) can filter thread(s) messages by recipient IDs. Very useful when trying to identify if a member already messaged another.

Props imath and slaFFik.

See ​https://github.com/buddypress/BP-REST/issues/455
Closes ​https://github.com/buddypress/buddypress/pull/394
See #9229 and #9145
Fixes #9157

[espellcaste]

In 14070:

A user is no longer de-authenticated when making REST API requests.

We are introducing a new BP_LoggedIn_User class to fetch data about a BuddyPress logged-in user. This new addition fixes an issue where a user could be de-authenticated when making REST API requests.

Props dcavins, DJPaul, johnjamesjacoby, and imath.

Closes ​https://github.com/buddypress/buddypress/pull/395
See #9229 and #9145
Fixes #7658

[espellcaste]

In 14071:

Misc changes to the signups and pending accounts.

We are improving how signups and pending accounts are handled in BuddyPress.

• activation emails resend are blocked for one hour, by default;
• emails are checked if they are already in use in a signup;
• signup endpoint (​https://developer.buddypress.org/bp-rest-api/reference/signup/) returns a useful error when feature is disabled;
• Signup::resend: Added the ability to resend to a single ID, instead of an array of IDs.

Props niftythree and imath.

Closes ​https://github.com/buddypress/buddypress/pull/396
See #9229 and #9145
Fixes #9137