Add Client and Provider to Hook Requirement 1.3

[beeme1mr]

Objective

Extend the list of immutable properties to include the client and provider.

NOTE: There's a proposal to change how the provider is exposed to hooks. That issue should be addressed before working on this one.

Reference

• https://cloud-native.slack.com/archives/C0344AANLA1/p1653656323342869

[justinabrahms]

This would mean that we would expect hooks to not add other hooks to the client and, if/when #75 lands, they shouldn't be able to alter the evaluation context in the client or API.

I think this seems fine, just want to call that out explicitly.

[toddbaert]

I think https://github.com/open-feature/spec/issues/84 makes this redundant.