Merge sidecar binaries into one

[SaiProServ]

The sidecar binaries were separated soon after a PR was opened in the event-sidecar repo, but the original plan was to distribute event stream and RPC sidecar as a single binary, so the PR should be adjusted to build a single binary instead of two. This will involve changing the app entry-point and merging the configs.

[jacek-casper]

implemented in https://github.com/zajko/event-sidecar/pull/6

[jacek-casper]

the underlying changes have been merged into the main sidecar pull requests:
casper-network/casper-sidecar#231
#4491