[Feature] Multi-partition support for AMIUpdater (update-ami)

[andrew-glenn]

The current taskcat update-ami config format is not partition aware. The proposal is to revamp the config to be partition-aware.

Current:

RHELHA83HVM:
  name: RHEL_HA-8.3_HVM-????????-x86_64-?-Hourly2-GP2
  owner-id: '309956199498'

Proposed:

RHELHA83HVM:
  name: RHEL_HA-8.3_HVM-????????-x86_64-?-Hourly2-GP2
  partition:
    aws: 
      owner-id: '309956199498'
    aws-cn:
      owner-id: '0123456789012'
    aws-us-gov:
      owner-id: '0123456789013'

If owner-id found in <mapping>.keys(), the default partition is aws, for backwards compatibility.

/cc @davdunc for commentary, as his use-case/team buy-in is critical

[andrew-glenn]

Thought: May need to account for situations where AMI wildcards are not consistent across partitions.