Allow readonly string arrays in types.enumeration

[jamonholmgren]

Overview

This PR enhances the enumeration function types to accept both mutable (string[]) and immutable (readonly string[]) string arrays. This allows for better compatibility with as const syntax and provides a more flexible API for users.

Fixes #1314.

Changes

• Updated the type signatures in the enumeration function to handle both readonly string[] and string[].
• Added new test cases to verify support for readonly string[] as well as maintaining support for string[].

Impact

These changes enable developers to use as const syntax with the enumeration function without any type errors, providing a smoother development experience.

Testing

New tests have been added to ensure that both readonly and plain string arrays are handled correctly. Note that tests don't seem to fail even when the typescript changes haven't been implemented, but there is a type error in the test in VS Code that goes away once this is implemented.

[coolsoftwaretyler]

Hey @jamonholmgren - this looks good to me and makes sense! I'm gonna merge it and include in the second RC for 5.2.0.