feat(config): Add Validation to Several Config Fields

[george-sentry]

Linear

Refs STREAM-843

Description

Some configuration options have specific requirements, like they must be greater than zero or a power of two. Until now, we've relied on ad hoc assertions and calls to functions like max(1) to enforce these constraints. I think it would be better to guarantee these constraints immediately on startup because ad hoc checks can easily be forgotten.

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[untitaker]

validation annotations are good, please make sure the design is still consistent with #663 where we have another validation method on Config

[untitaker]

one thing to think about: impl Validate for Config inherently exposes a public validation function. is there a way to make it private (and call it in validate_and_normalize), or maybe validate_and_normalize can be made private and called via this validate crate?

https://github.com/Keats/validator/blob/master/README.md#struct-level-validation

[linear-code]

STREAM-843

[untitaker]

@george-sentry I think we should not have two of these functions. normalize_and_validate is called from tests, and in those tests we should call validate too IMO