feat(rpc): implement Filecoin.StateMinerInitialPledgeCollateral

[elmattic]

Summary of changes

Changes introduced in this pull request:

• Add Filecoin.StateMinerInitialPledgeCollateral RPC method

forest-tool api compare --lotus /ip4/127.0.0.1/tcp/1234/http --forest /ip4/127.0.0.1/tcp/2345/http forest_snapshot_calibnet_2024-04-25_height_1556655.forest.car.zst --filter Pledge
| RPC Method                                      | Forest | Lotus |
|-------------------------------------------------|--------|-------|
| Filecoin.StateMinerInitialPledgeCollateral (16) | Valid  | Valid |

Reference issue to close (if applicable)

Closes #4213

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.