Wiring for Custom datadir

[D33r-Gee]

Please describe the feature you'd like to see added.

Backend wiring so that a user can select a custom data directory (other than ~/.bitcoin).

This was attempted in #408 however the restructuring and refactoring of src/qml/bitcoin.cpp doesn't seem to be the best approach.

Ideally it requires a deep understanding of the cpp code related to bitcoin node initiation and qml connections.

Ubuntu Screenshots of #408

Is your feature related to a problem, if so please describe it.

N/A

Describe the solution you'd like

The ultimate solution would involve the ability to pick a custom data directory while onboarding.

Also if the user uses the command line argument -datadir="path_to_custom_datadir" it should display in the Storage Settings page.

It should for both desktop and android.

Describe any alternatives you've considered

Previous work related to this were explored in PRs #390 #392 #397 and the now closed #408

Please leave any additional context

No response