Respect pre hook for relationship to alter id in $params

[pradpnayak]

Overview

If we alter the $params['id'] in pre hook then its not respected by CRM_Contact_BAO_Relationship::add() function. This PR allows hook to alter id.

[eileenmcnaughton]

@pradpnayak I worry that this isn't robust & could be changed at any point, breaking any extensions that rely on it, since there is no specific contract / commitment to permitting id to be altered. 2 ways to protect it are

1. by using code practices as standardised as possible - in this case perhaps merge in the defaults first & then do per code comment

 //@todo this code needs to be updated for the possibility that not all fields are set
    // by using $relationship->copyValues($params);

2. unit tests

[eileenmcnaughton]

@totten @colemanw what do you think of this - I get why people would want it - but it seems to be ad hoc expanding our hook support contract (I don't think this is the first place that has been done but the concern still applies) - perhaps we need a generic syntax conformance test & to add it as a standard rather than an ad hoc approach. Note that adding Syntax conformance doesn't mean making it work for EVERY entity - it means doing the easy ones & setting the others to be skipped

[colemanw]

IMO this is consistent with other places in our codebase where we are working to deprecate the $ids param in BAO add/create functions. So I'm good with merging this with one caveat, I think we should remove the & from the function signature so it reads public static function add(&$params, $ids = array(), $contactId = NULL) {. If we are going to modify the array, we should not take it by reference.

[pradpnayak]

jenkins test this please

[eileenmcnaughton]

I'm going to merge based on @colemanw's review - my caution remains that this handling of $params['id'] is not locked in by tests or by our hook contract & could change at any time so extensions that rely on it need to implement their own unit testing to warn them if it does change