Harmonize Password C (LND/CL)

[rootzoll]

There is a password to lock the LND wallet and one to decrypt c-lightning (optional) - both are called password C but because the password itself is not stored in the device, because that would make the physical security that one once to gain from that password obsolete. But we need a way to make sure those both are really the same and are in in sync.

Also the same with the SSH password & with the WebUI - see #2482

We could write a small script that can create a password-hash file that contains a salt & hash of the password C. This file is created if password C (setup) is set by the user or the user used an entered password C sucessfully to unlock/decrypt a wallet (update). Now RaspiBlitz could test quickly before setting the password on the other service if its the same password C as already set on the other service before doing it.

[openoms]

I like the concept, but will need to see if there is anyone using CL alongside LND with significant value in both which would justify using the wallet encryption and no autounlock.

Autounlock for both CL and LND has the password stored on the disk.