feat : add jobs pallet rpc calls

[1xstj]

Summary of changes
Changes introduced in this pull request:

• Adds jobs pallet rpc calls

How to use

Example : queryNextJobId

curl -H "Content-Type: application/json" -d '{"id":1, "jsonrpc":"2.0", "method": "jobs_queryNextJobId", "params": [null]}' http://localhost:9944/
{"jsonrpc":"2.0","result":1,"id":1}

Example : queryJobsByValidator

curl -H "Content-Type: application/json" -d '{"id":1, "jsonrpc":"2.0", "method": "jobs_queryJobsByValidator", "params": [null, "5GrwvaEF5zXb26Fz9rcQpDWS57CtERHpNehXCPcNoHGKutQY"]}' http://localhost:9944/
{"jsonrpc":"2.0","result":[{"job_id":0,"job_type":{"DKGTSSPhaseOne":{"participants":["5GrwvaEF5zXb26Fz9rcQpDWS57CtERHpNehXCPcNoHGKutQY","5FHneW46xGXgs5mUiveU4sbTyGBzmstUspZC92UhjJM694ty","5FLSigC9HGRKVhB9FiEo4Y3koPsNmBmLJbpXg2mp1hXcS59Y"],"threshold":1,"permitted_caller":null,"role_type":"TssGG20"}},"participants":null,"threshold":null,"key":null}],"id":1}

Reference issue to close (if applicable)
Part of #302

[drewstone]

Left comment. If intentional it LGTM.

[tbraun96]

Tested this PR locally on the ECDSA gadget branch, and it works.

[shekohex]

LGTM!