Ability to select user roles when picking a user, e.g. Component Lead, via smart-values, user fields, etc.

Use cases:

• For assignee fields, send email
• Notify members of a project role (also see AUT-262 Done )
• User conditions (see AUT-217 Done )

We should have something like:

{{issue.project.roles.My Awesome role.users}}

perhaps.

We should allow Component Leads to be used in:

• Smart-values
• User fields
• Watchers
• Outgoing emails
• Assign

Components smart value should include description & component lead

Action to set a lead for a component - Looks like there's a REST endpoint to update components