`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.
- btcpayserver: remove unneeded trailing semicolons
- krops/get-sha256:
`tail` is unneeded because `nix-prefetch-url` just outputs a single
line containing the hash.
Use the following order of definitions for all services:
- assertions
- configuration of other services
- environment.systemPackages
- tmpfiles
- own service
- users
- secrets
Systemd's `Description` option is a misnomer (as confessed by `man systemd.unit`):
Its value is used by user-facing tools in place of the unit file name, so this option
could have been more aptly named `label` or `name`.
`Description` should only be set if the unit file name is not sufficient for naming a unit.
This is not the case for our services, except for `systemd.services.nb-netns-bridge`
whose description has been kept.
As an example how this affects users, weird journal lines like
```
nb-test systemd[1]: Starting Run clightningd...
```
are now replaced by
```
nb-test systemd[1]: Starting clightning.service...
```
