Handle the case where enhanced measurement settings are changed on Analytics after setting them in Site Kit.

[techanvil]

Feature Description

If enhanced measurement settings are changed on Analytics after setting them in Site Kit, the implication is that any configured ECCT widget tile that depends on enhanced measurement may be affected.

We need to consider how to handle this scenario:

1. We could track the configured state in Site Kit and then show a banner to update it in Site Kit if there are changes on the Analytics side.
2. If the user sets up an ECCT widget tile that depends on a given enhanced measurement setting being enabled and it's subsequently disabled on the Analytics side, then we show a banner to prompt the user to re-enable it.

The first approach would require a bit of extra server-side state and some polling of the EM settings, whereas the second approach seems like something we might want to build into the ECCT feature anyway. Therefore it might simply be better to handle this in the ECCT epic too (see #7476).

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