[cmd/mdatagen] Support JSON Schema validation rules in generated Go config code

[jkoronaAtCisco]

This is an umbrella issue to track the implementation of JSON Schema validation rules in Go code generated by mdatagen from component config schemas.

The goal is to extend mdatagen's code generation so that validation constraints defined in JSON Schema are enforced at runtime through generated Go Validate() methods.

Sub-issues

• [cmd/mdatagen] Implement enum and const validation in generated Go config code #14805 — Implement enum and const validation
• [cmd/mdatagen] Implement numeric validation in generated Go config code #14806 — Implement numeric validation (minimum, maximum, exclusiveMinimum, exclusiveMaximum)
• [cmd/mdatagen] Implement string validation in generated Go config code #14807 — Implement string validation (minLength, maxLength, pattern)
• [cmd/mdatagen] Implement array validation in generated Go config code #14808 — Implement array validation (minItems, maxItems, uniqueItems, contains)

[github-actions]

Pinging code owners:

• cmd/mdatagen: @dmitryax

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