This adds two new commands: `publish-webapp-deployer` and `request-webapp-deployment`.
`publish-webapp-deployer` creates a `WebappDeployer` record, which provides information to requestors like the API URL, minimum required payment, payment address, and public key to use for encrypting config.
```
$ laconic-so publish-deployer-to-registry \
--laconic-config ~/.laconic/laconic.yml \
--api-url https://webapp-deployer-api.dev.vaasl.io \
--public-key-file webapp-deployer-api.dev.vaasl.io.pgp.pub \
--lrn lrn://laconic/deployers/webapp-deployer-api.dev.vaasl.io \
--min-required-payment 100000
```
`request-webapp-deployment` simplifies publishing a `WebappDeploymentRequest` and can also handle automatic payment, and encryption and upload of configuration.
```
$ laconic-so request-webapp-deployment \
--laconic-config ~/.laconic/laconic.yml \
--deployer lrn://laconic/deployers/webapp-deployer-api.dev.vaasl.io \
--app lrn://cerc-io/applications/webapp-hello-world@0.1.3 \
--env-file ~/yaml/hello.env \
--make-payment auto
```
Related changes are included for the deploy/undeploy commands for decrypting and using config, using the payment address from the WebappDeployer record, etc.
Reviewed-on: #938
