Multiple email activity cc recipients get scrunched together in recorded activity details field

Recently refactored and the comma separator went missing: https://github.com/civicrm/civicrm-core/commit/a01fb99f56574eae7b6ade7cbb4f3292c505fe7d#diff-e604b19bd1979412f2455096459e761bR411-L439

https://github.com/civicrm/civicrm-core/blob/b3925388349a3d356b8852ead72361123e3ed196/CRM/Contact/Form/Task/EmailTrait.php#L564

Also the contact link url contains force=1 which seems unnecessary.

1. Send an outbound email in civi to multiple cc recipients.
2. Look at the details field on the recorded activity.

I can do a PR - came up while reviewing https://github.com/civicrm/civicrm-core/pull/18299