fix(cli): dont fail hard on integer based enums

[dsinghvi]

Description

The OpenAPI parser assumed that enums would alwyas be strings but now handles cases with integers.

Changes Made

• openapi-types types schema.enum as any[] which made this impossible to detect
• check if the enum is a string and then convert to a fern enum
• otherwise bring in as an alias b/c fern definitions dont support integer enuyms

Testing

• Unit tests added/updated
• Manual testing completed