Implement endpoints for token module

[nagdahimanshu]

Description

Implement endpoints for token module
There is need to implement similar endpoint like getTotalSupply to retrieve stakedLSK, inflationRate and totalSupplyLSK
This information can be included in blockchain application stats endpoint response by lisk-service.

Endpoints:

• getStakedLSK
• getInflationRate
• totalSupplyLSK

Acceptance Criteria

• Suggested endpoint is added to token module
• Add unit test for all the endpoints

[shuse2]

getInflationRate, we can include the endpoint with #7622 which will be exposed under reward module

getStakedLSK, I think this will go under DPoS, but since this will require to iterate through all the votes, I don't think we can expose this value from endpoint

totalSupply is already exposed by token module getTotalSupply, if LSK specifically from sidechain, i don't think sidechain can know the total supply of LSK.

[shuse2]

Closing this issue since this is no longer valid