Allow editing Capture autoDiscover properties

[psFried]

estuary/flow#1078 adds the autoDiscover properties to Capture specs. These allow users to opt in to periodic background discover operations that get automatically published. The UI should allow users to set these properties during capture creation, and also edit them for existing captures.

• AutoDiscover can be enabled or disabled
  • Enabled is represented as any non-null value of autoDiscover, such as autoDiscover: {} or autoDiscover: {addNewBindings: false}
  • Disabled is represented as either null or undefined. Though we technically need to support both of these for compatibility, we should prefer an explicit null
• addNewBindings determines whether to add newly discovered bindings to the capture. If false, then it will only ever update existing bindings. If true, then it will both add new bindings and update existing ones. There's no option for adding new bindings without also updating the existing ones.
• evolveIncompatibleCollections determines the behavior of the publications handler when a newly discovered collection is rejected due to being incompatible. If true, then a failed publication due to incompatible collection changes will automatically trigger an evolutions job and a subsequent publication of the updated draft. If false, then the publication will just fail and that'll be the end of it. (Eventually, we'll need alerting for the latter case, but we'll discuss that later.)