fixes #256 - btc-node-config via env-vars

[k9ert]

copied from the info-popup below:

When auto-detect is on, Specter will check for Environment-Variables (BTC_RPC_USER, BTC_RPC_PASSWORD, BTC_RPC_HOST, BTC_RPC_PORT) to configure the connection or attempt to automatically locate your Bitcoin data
directory and load your node configurations from it.

[k9ert]

Usually you probably use the env-vars if you connect to a remote-host. That should be https by default. If you really want to do something stupid (e.g. for testing reasons) you can still specify BTC_RPC_PROTOCOL=http .

[k9ert]

copied from the other issue. PR+issues is confusing to me in Github.

Looks good, I just don't understand why https by default - it will break autodetect for local nodes...

Not sure i understand your concern. If the env-vars are specified, local-autodetection is no longer used anyway.
Note that the env-solution will only work if all 4 env-vars are defined. Otherwise i hope everything else works as before.
https://github.com/k9ert/specter-desktop/blob/rpc-envvar-config/src/cryptoadvance/specter/rpc.py#L123-L135
It returns an empty array if not all 4 (but not the protocol) is defined.
At least that was my intention. So shouldn't break the autodetection?

[stepansnigirev]

Oh, got it. Then it should be fine, sorry!