feat(payment-detection): add minIndexedBlock option for TheGraph

[alexandre-abrioux]

supersedes #1253

Context

When using TheGraph decentralized network, different GQL queries can target different indexers. For consistency, we can ask to target only indexers that have processed specific blocks using a block filter.

For more info, see here or here, look for number_gte in these pages.

Description of the changes

• Added a new minIndexedBlock option to TheGraph client in order to handle this

[coveralls]

coverage: 87.098%. remained the same
when pulling 586ca8f on subgraph-min-indexed-block-v2
into 9c9a2c1 on master.

[benjlevesque]

suggestion: add a method getTheGraphClient(network, url, options) that deals with the near/evm condition:

const getTheGraphClient = (network:string, url: string, options?: TheGraphClientOptions) => NearChains.isChainSupported(network) ? getTheGraphNearClient(url, options) : getTheEvmGraphClient(url, options);