Add "responsible contacts" to checklist from internal/master contact list and auto-update lead/project directory

There are multiple potential solutions to the issue at hand here, I am merely presenting a solution that seems logical from an end-users perspective.

As stated in SAGECM-I-553, we utilize checklists for many internal workflow related items. In doing so, we frequently need to choose internal contacts as the "responsible contact". Currently, we are only able to select from the "Lead/project contacts" and this creates a lot of extra steps for us - always having to update the lead/project directory to include the internal contacts for our internal workflows.

Ideally, i would be able to select other contacts directly from the checklist, and by adding them to the checklist, it would automatically update the lead/project directory.