[gRest] /datum_info endpoint

[dostrelith678]

Description

Adding an endpoint for getting datum information based on its hash. Currently returns only the datum value in JSON and bytes format. We could add more to it in the future, for now, it seems to be all that's needed.

To consider: make this endpoint accept a list of hashes as bulk input?

Which issue it fixes?

Closes https://github.com/cardano-community/koios-artifacts/issues/86

How has this been tested?

Tested endpoint on guildnet.

[rdlrt]

make this endpoint accept a list of hashes as bulk input

Would agree , as it's a simple table, makes sense to add bulk query ability