Is your feature request related to a problem? Please describe.
As part of the implementation of the embedded CL for OP Stack chains we need to support the optimism RPC methods.

Describe the solution you'd like

• Add the optimism RPC methods according to the spec: https://docs.optimism.io/operators/node-operators/json-rpc
• Support this namespace by default in OP Stack chains.
• Add the corresponding tests.

Describe alternatives you've considered
Not implementing the feature.

Additional context
This feature is required according to the milestones defined for the OP CL project.