fix: refactor ToIdentifier() to normalize flaggable enums

[MaggieKimani1]

• Adds support for normalizing flaggable enums by returning an array of strings
• Supports casting of type arrays to the flaggable enum type
• Adds tests to validate

Fixes #2078
Fixes #1924

[baywet]

Thank you for making the changes!
A couple of additional remarks for performance.

Note: we could also use frozen dictionary for the static reference but I'm not sure the extra dependency is worth it.