Additional options for controlling alert banner visibility

[amcclain]

In addition to current expires and client apps filters in the admin alert banner spec, would like to add:

• Limit to role(s)
  • Would allow a banner targeted to e.g. users of a particular section within the app, or internal users only (for an app that has a mix of internal company and external guest users)
• Limit to app version
  • Would support easier banner takedown after e.g. a hotfix release. Could include convenience button for admin to populate with current version (this would be the expected use case) - banner will then automaticaallly not show right after release and refresh, without needing to get timing right or rush to remove immediately before/after
  • No need for fancy version ranges or anything like that - exact match should be all we need

Would group these together with existing client app field in a new "limit to" section.