* Rename serverkeyapi to signingkeyserver
We use "api" for public facing stuff and "server" for internal stuff.
As the server key API is internal only, we call it 'signing key server',
which also clarifies the type of key (as opposed to TLS keys, E2E keys, etc)
* Convert docker/scripts to use signing-key-server
* Rename missed bits
* Update INSTALL.md
* Move some things
* Clean up
* Move some more things
* Don't build all the things for the monolith
* Update INSTALL.md
* Nuke hooks
