fix: typecheck and fix internal types

[bluwy]

Description

Fixes #234

Enabled typechecking for the .js files. Honestly, it doesn't seem like the library was written with typesafety in mind. I have to make a lot of fixes.

There's 2 possible/small breaking changes that I've left as TODO that can be fixed later or here depending on what solution you'd like to go with.

There's one small breaking change made in this PR needed to appease a lot of the internal types:

export interface TSConfckParseOptions extends TSConfckFindOptions<TSConfckParseResult> { ... }

export interface TSConfckParseNativeOptions extends TSConfckFindOptions<TSConfckParseNativeResult> { ... }

The cache property for these two options are now stricter (using the generics) so internally it's correctly accessing the properties.