Add the 'raw' argument with the 'm2m_changed' signal

[Élie Bouttier]

The 'raw' argument is sent with pre_save and post_save signals in order to detect fixture loading and avoid un-needed operations in this case.
Unfortunatly, this argument is not sent with m2m_changed signal !
I find a work-around on stack-overflow for tests which consist in disconnecting the m2m_signal in the setUpClass.
However, this is not applicable for loaddata management command.

Please send the 'raw' argument with the m2m_changed signal, this is needed!

[Tim Graham]

This was also proposed in #17583 which was marked as a duplicate of #8399 but I don't see an elegant solution in that ticket, so maybe it's time to accept this.

[Mariusz Felisiak]

​PR

[Mariusz Felisiak <felisiak.mariusz@…>]

In c3b6c296:

Refs #27380 -- Made ManyRelatedManager.add()/clear()/remove() implementation more consistent.

This also adds _add_base(), _clear_base(), and _remove_base() internal
hooks.

[Mariusz Felisiak <felisiak.mariusz@…>]

In 6fc2406:

Refs #27380 -- Made ManyRelatedManager.set() use *_base() hooks.

[Mariusz Felisiak <felisiak.mariusz@…>]

In 12d5744:

Refs #27380 -- Added ManyRelatedManager.set_base() hook.

[Mariusz Felisiak <felisiak.mariusz@…>]

In 4702b36:

Fixed #27380 -- Added "raw" argument to m2m_changed signals.

[Jacob Walls <jacobtylerwalls@…>]

In 5a851bdb:

Refs #27380 -- Added release note for raw argument to m2m_changed signal.