`generate-secrets` is no longer a monolithic script. Instead, it's
composed of the values of option `nix-bitcoin.generateSecretsCmds`.
This has the following advantages:
- generate-secrets is now extensible by users
- Only secrets of enabled services are generated
- RPC IPs in the `lnd` and `loop` certs are no longer hardcoded.
Secrets are no longer automatically generated when entering nix-shell.
Instead, they are generated before deployment (via `krops-deploy`)
because secrets generation is now dependant on the node configuration.
Now that service uid, gid mappings are included in the backups, along
with the service data dirs, we can remove 'chown -R' for
clightning and liquidd data dirs.
Note that we used 'chown -R' only for these two services, while this
approach would have been relevant for all services with data dirs.
Keeping the secrets dir read-only is more simple and robust.
- lnd seed mnemonic creation and joinmarket wallet creation can be
run as the regular service user instead of root.
- It is easier to switch to a third-party secrets deployment
method in the future.
Don't create a seed mnemonic for lnd when a wallet exists.
This avoids creating unused mnemonics and helps simplifying
the migration command in `versioning.nix`.
