fix(bug): call._setPrimary should set _primary before _emit is sent

[skyler-murray]

Description

Ran into this while testing out multiple call handling. This fixes a subtle bug where we set _primary after sending the event so the event and the call list didn't have a primary call set. This is due to the this._emit('promoted', this) being called before we set the call to primary and so all the data in the event has no primary call set.

My argument for doing this is that at this point the call has become the primary and should be reported as such with the event. The call.demoted logic follows the same pattern and sets this.primary = false before sending the demoted event.

Scenario:

1. You have two active calls (A, B). One is on hold (B) while the primary (A) is either on hold or not (it doesn't matter).
2. Call lwpCallList.switchCall(B.callId()) to make B the active call
3. A gets put on hold
4. B is promoted to primary and no longer on hold
5. Received call.promoted event for B

Expected:
call.isPrimary() for B returns true
_lwp.getCallList() returns a list of calls [A, B] and B.isPrimary() === true

Actual
call.isPrimary() for B returns false
_lwp.getCallList() returns a list of calls [A, B] and B.isPrimary() === false