Improve utilities around replace.toml generation and sidecar

Possible generation examples with modes of validator, normal, high-performance-rpc, high-performance-sse.

How do we integrate changes needed with sidecar changes?

Possibly hold a sidecar replacement in /etc/casper-sidecar which can be run against the sidecar config.

Use of builder pattern to allow commands to put certain common use cases in replace.toml.