feat(bmr): allow additional parameters for endpoint in relay configuration

[MuhammedIrfan]

Overview

Currently relay config only accepts string for endpoints. Certain chains like near protocol have multiple type of nodes, such as archival node and full node. Full node garbage collects the blocks each 5 epochs, older blocks hence need to be queried from archival node. Having extra config to describe the type of node along with endpoint can enable the relay to seamlessly switch the client based on the type of node for older blocks and balance load between multiple endpoints.

Story

As a Relay Operator, I want to configure the type for endpoints so that older blocks can be queried using archival nodes and block with in 5 epochs can be queried using either nodes for load balancing

Acceptance Criteria

• Provision to provide extra config to describe the type of node