Implement Eth Event Filter API's

[sudo-shashank]

Summary of changes

Changes introduced in this pull request:

• Implemented eth event filter rpc and added test against lotus

| RPC Method                      | Forest | Lotus |
|---------------------------------|--------|-------|
| eth_newBlockFilter              | Valid  | Valid |
| eth_newFilter                   | Valid  | Valid |
| eth_newPendingTransactionFilter | Valid  | Valid |
| eth_uninstallFilter             | Valid  | Valid |

Reference issue to close (if applicable)

Closes

Other information and links

Change checklist

• I have performed a self-review of my own code,
• I have made corresponding changes to the documentation,
• I have added tests that prove my fix is effective or that my feature works (if possible),
• I have made sure the CHANGELOG is up-to-date. All user-facing changes should be reflected in this document.

[LesnyRumcajs]

@sudo-shashank can we split it into smaller PRs with every method handled separately? It will be easier to review and outstanding comments in one issue wouldn't block another. It's also a good practice to try to limit the PR size (if possible).

[sudo-shashank]

@sudo-shashank can we split it into smaller PRs with every method handled separately? It will be easier to review and outstanding comments in one issue wouldn't block another. It's also a good practice to try to limit the PR size (if possible).

yes sure