Typescript: allow omitDeprecatedEnumCases (@deprecated directive)

[According to the docs](https://github.com/apollographql/apollo-tooling#apollo-clientcodegen-output), `apollo client:codegen` has an option to ignore deprecated values in enums (`omitDeprecatedEnumCases`), but that is only supported using swift.

I'd really need this implemented for typescript too.
Or is there any other way to remove deprecated enums from the generated types?

Start with the apollo client:codegen command and inspect how the omitDeprecatedEnumCases option is handled for Swift. Trace the TypeScript generation path and determine where deprecated enum values are retained. Done means TypeScript output supports the option and omits enum cases marked with the @deprecated directive.

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