support plain text on enum validated params

[mazen-r]

Related issue: #9
Support plain text on params with enum since the config is generated as plain text on the API player.

[Granitosaurus]

@mazen-r I think we should use literal string values instead of any string to be more idiomatic with typescript. e.g. we should use:

format_options?: ("no_links" | "no_images" | "only_content" | FormatOption)[];
// instead of current:
format_options?: string[] | FormatOption[];

This will prevent users from making mistakes in string options while retaining all type checking.

Tbh I'm not sure what's the use of Enums are these days and string literal types would actually be prefered over Enums every single time except when names change often. Though I don't think we can drop support for Enums in case someone is using this feature already but we can incentivise string use if we put the string type hints before the enum one (like the example above)

So, this PR should be updated to hint string types with literal values where it's appropriate.

[mazen-r]

@Granitosaurus yeah good point, updated accordingly. Enums were a requirement in the Python SDK since Python doesn't have type-checking capabilities and I followed the same approach here. Also, not all users use TS so string type hints maybe ineffective for such cases.