Remove contact tags when none selected on edit screen

[pradpnayak]

Overview

Contact are not untagged when all the values from tag select drop down is unselected.

Steps to reproduce:

Log in to CRM
Go to Individual's profile
Click the button "Edit"
Open block "Tags and Groups"
Delete data from field "Tag(s)"
Click the button "Save"
Result: The information in the tag field is not updated (see below gif file)

Expected result: The field "Tag(s)" has been updated.

Before

After

Technical Details

When Tags are unselected on Contact edit form $params['tags'] is empty and hence it doesn't call create entity tag function where it removes or adds tags depending upon $params['tags'] array passed. The create entity tag function first gets all the tags of the contact and then diff with $params['tags'] and untags the contact from result of diff.

[civibot]

(Standard links)

• If this is your first pull-request for CiviCRM, please browse CONTRIBUTING.md for information about the development and testing processes.
• If you are reviewing this pull-request, you may wish to consult the test sites and the Review Standards (long template, short template).

[eileenmcnaughton]

@pradpnayak did you forget to fill in the pr detail?

[pradpnayak]

@eileenmcnaughton Sorry! I just updated it.

[colemanw]

Unrelated test fails.

[colemanw]

I'm merging this to 5.7 as it appears to be a recent regression.

[eileenmcnaughton]

@colemanw we are probably dropping a 5.6.x - see #12965 - should we pull this in?

[colemanw]

I'm good with that @eileenmcnaughton