[Team] Add Jira Instances

[StevenWeathers]

Add the ability for a subscribed Team to setup a shared Jira Instance for its members to use in Thunderdome features.

[scottux]

Same comments as #514 but for teams, and then extended to ask about trickle down instances.

[StevenWeathers]

To clarify, teams can live outside organizations so this is meant to offer the same functionality to those teams. Same rules apply as far as Team Admins manage the team associated instances, and end users wouldn't have visible access to the API key.

Essentially the whole idea is that when a feature will interact with Jira, the user will have the option to select a Jira Instance from a dropdown that has their user account associated Jira instances, Team, and Organization (These can be separated in the dropdown as to be clear which instances they're consuming). The Instance ID is then passed in the subsequent calls and the backend gets the API key from DB therefore never needing to expose the key to the end user.