handle validation

[clux]

kube-derive supports using schemars + validator to inject validation rules into the schema.

We should similarly parse the validation attributes from the schema, and store them as properties on OutputMember, so we can (optionally) add them to the generated code. (See crd_api example for how the output is supposed to look (ignore the deprecation attrs)).

Fields to look for (that we currently do not cover):

• exclusiveMaximum
• exclusiveMinimum
• maximum
• maxItems
• maxLength
• minimum
• minItems
• minLength
• multipleOf
• pattern
• uniqueItems

These are mentioned in the kubernetes crd docs.

Don't think we can verify all of them, but should be able to do min/max stuff + patterns with some of the basics from validator. Partial attempts at some of the properties is welcome.

At the very least this needs:

• flags for OutputMember to store information found during analysis
• --validation bool flag for cli to optionally enable it
• crd with a test case for CI