Health Check against an instance using CLI

It would be nice to have a a healthcheck ping from CLI against a specific instance (eg: `-b http://127.0.0.1:8053/api/v0` , that will check and report stats below behind the scenes (currently achieved via bash script [grest-poll.sh](https://github.com/cardano-community/guild-operators/blob/alpha/scripts/grest-helper-scripts/grest-poll.sh) ):

- [x] Query target's `tip` to check that the last block known to instance is within 600 seconds, use timeout of 2 seconds to establish connection to this endpoint (anything more being too slow to accept connection)
- [ ] Be able to verify (using `/` endpoint) that each path from spec is available at the target instance (current implementation [here](https://github.com/cardano-community/guild-operators/blob/alpha/scripts/grest-helper-scripts/grest-poll.sh#L101-L117))
- [x] Check every record in control table to check they're relatively recent (see [here](https://github.com/cardano-community/guild-operators/blob/alpha/scripts/grest-helper-scripts/grest-poll.sh#L119-L144) )
- [x] Check Observation [limit is uniform](https://github.com/cardano-community/guild-operators/blob/alpha/scripts/grest-helper-scripts/grest-poll.sh#L146-L152)
- [x] Do a [Get/POST to test a sample request](https://github.com/cardano-community/guild-operators/blob/alpha/scripts/grest-helper-scripts/grest-poll.sh#L154-L169)
- [x] Optionally - at the end of it all, with a debug argument (eg: `-d` ), provide a summary of the endpoint results.
- [x] Exit with return code 1 if any of the tests fail, and 0 if they all pass.

If all of the above is achievable, this will help us use something like `koios-cli healthcheck [-d]` for actual healthcheck from haproxy itself, as an alternative to using bash script we currently use.