Silence spammy blueprint warnings and validate blueprint on load

[jleibs]

What

• Resolves: Fix deserialization log spam when trying to load old blueprint #4299

Adding a helper to silence the error messages only solved half the problem. Nothing prevented this corrupt data from being removed from the store, and worse, in some cases the corrupt data subsequently prevented new writes.

We now validate that all the data in the blueprint has a valid schema or else we refuse to load it.

Checklist

• I have read and agree to Contributor Guide and the Code of Conduct
• I've included a screenshot or gif (if applicable)
• I have tested demo.rerun.io (if applicable)
• The PR title and labels are set such as to maximize their usefulness for the next release's CHANGELOG

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