feat: allow specifying regions/accounts at a more granular level

[echeung-amzn]

This allows users to target different regions/account for specific things within a facade rather than relying on 1 facade per region/account with the facade's global settings, so something like:

this.facade
  .monitorDynamoTable({
    ...,
  })
  .monitorDynamoTable({
    ...,
    region: <some_other_region>,
    account: <some_other_account>,
  })

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