How do we customise the generated declaration files to emit complex typescript types that the compiler might not know what to do

When using DNT to generate declaration files for a TypeScript project, there is currently no straightforward way to customize the emitted types for complex scenarios where the TypeScript compiler might not have enough information to infer the correct types. We need a mechanism to specify custom typings to be included in the generated declaration files.

To address this limitation, it would be helpful if DNT allows developers to provide custom TypeScript type declarations that can be included in the generated declaration files. This way, developers can manually define the types for complex scenarios where the TypeScript compiler's inference may fall short.