feat: Enforce required tags in SSM store

[bhavanki]

The behavior is as follows:

• When writing a new secret, all required tags must be provided.
• When writing tags to a secret, and other tags are being deleted, then all required tags that are already present on the secret must be provided.
• When deleting tags from a secret, required tags may not be provided.

The second item is a bit subtle. If other tags aren't being deleted, i.e., tags not provided are being left alone, then required tags don't have to be provided (they may be, but don't have to be). Also, if other tags are being deleted, then the only required tags that have to be provided are those that are already set. These behaviors are designed so that after a store's configuration is updated to require tags, you don't have to then immediately set them all on every existing secret. Once you do set them though, you can't get rid of them.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 85.45455% with 8 lines in your changes missing coverage. Please review.

Project coverage is 37.33%. Comparing base (c2d3399) to head (7b2348b). Report is 5 commits behind head on master.

Files	Patch %	Lines
store/ssmstore.go	88.00%	3 Missing and 3 partials :warning:
store/store.go	60.00%	1 Missing and 1 partial :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #548 +/- ## ========================================== + Coverage 36.34% 37.33% +0.99% ========================================== Files 29 29 Lines 2592 2646 +54 ========================================== + Hits 942 988 +46 - Misses 1567 1571 +4 - Partials 83 87 +4 ```

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