Separate filename from package name config

Currently, providing a `-p com.mypackage` option has 2 effects, which I strongly believe are different and should not be mixed.

1. it makes the generated top-level members part of the given package, adding the `package com.mypackage` statement at the top of the file. This is IMO the expected behaviour of this option.
2. it changes the output file's name to "${packageName}.module_${sourceModuleName}"

While 1) is exactly what I would expect, 2) prevents me from using Dukat on multiple files.

My goal is to convert a whole TS module and map it to a Kotlin package. If I provide the `-p` and `-m` options, and all `.d.ts` files of the module, Dukat overwrites the same file over and over because of behaviour 2).

Is there a way to provide options/arguments so that I can convert a whole module and have:

* the same `package` statement in all generated Kotlin files
* `@JsModule` for all files mapped to the module I'm converting
* different Kotlin files for different source `.d.ts` files (so that they don't overwrite each other)

?

Start by locating the `-p` and `-m` option handling and the output filename generation. Trace how multiple `.d.ts` inputs are converted, then verify that the package and `@JsModule` settings are shared while each source file produces a distinct Kotlin output without overwriting another.

Written by the indexing model from the issue text.