[PM] Minimize the dogecoin-specific source code

[Old Dip Tracker]

Describe the issue

The more source files we maintain that only or largely contain generic Bitcoin code, the more work we will face in the future when code gets optimized or has bugs fixed by upstream changes. It's therefore important to only maintain the files we really change for Dogecoin, and keep the source code to a minimum. We'll need some wrapper structs to achieve this in GoLang, but overall this is very possible.

Timing

I propose to postpone this maintenance item until we have a functional implementation that syncs all blocks and passes all the tests, so that until then, we have more flexibility and visibility of code that needs to be changed.