Fix the `@types/node-forge` for `asn1.integerToDer`

[vojtechsimetka]

Rationale

The current version of @types/node-forge is missing number of functions in the type definitions. This prevented us from using for example the asn1.integerToDer function here.

Tasks

• [ ] Review the https://github.com/DefinitelyTyped/DefinitelyTyped/tree/master/types/node-forge and what are the missing functions for the asn1 interface
• [ ] Add the missing functions and definitions and propose it to the https://github.com/DefinitelyTyped project
• [ ] Get the PR to be merged and update our types definition