Add alembic version endpoint

[raymondjacobson]

Description

Add /alembic_version endpoint that prints out

{
data: {
version_num: "be27a2794f75"
},
latest_chain_block: 3159,
latest_chain_slot_plays: 102,
latest_indexed_block: 3159,
latest_indexed_slot_plays: null,
signature: "0x99cb83eacfd3781d5319b83b9232d7257b44e15ba2fb3a3e8d3113f316e485097ed9cde1b8d49cc90e82717fa4161847279d872a1818834c190e9c2a4c84adfd1b",
signer: "0x15712a65ac707ae2ee3328c84fdca16b06d944c2",
success: true,
timestamp: "2022-01-11T07:38:32.172Z",
version: {
service: "discovery-node",
version: "0.3.49"
}
}

Tests

Local stack

How will this change be monitored?

Endpoint in prod