feat: implement Filecoin.GetParentMessages RPC API(server side)

[hanabi1224]

Summary of changes

As part of #3639

Changes introduced in this pull request:

• implement Filecoin.GetParentMessages RPC API(server side) that is compatible with lotus

Running `target/debug/forest-tool api compare /home/me/fr/snapshots/calibnet/forest_snapshot_calibnet_2023-11-16_height_1093103.forest.car.zst --filter ChainGet`
| RPC Method                             | Forest | Lotus |
|----------------------------------------|--------|-------|
| Filecoin.ChainGetBlock                 | Valid  | Valid |
| Filecoin.ChainGetBlockMessages (49)    | Valid  | Valid |
| Filecoin.ChainGetGenesis               | Valid  | Valid |
| Filecoin.ChainGetMessage (12)          | Valid  | Valid |
| Filecoin.ChainGetMessagesInTipset (20) | Valid  | Valid |
| Filecoin.ChainGetParentMessages (49)   | Valid  | Valid |
| Filecoin.ChainGetTipSet                | Valid  | Valid |
| Filecoin.ChainGetTipSetByHeight        | Valid  | Valid |

Lotus code:

func (a *ChainAPI) ChainGetParentMessages(ctx context.Context, bcid cid.Cid) ([]api.Message, error) {
	b, err := a.Chain.GetBlock(ctx, bcid)
	if err != nil {
		return nil, err
	}

	// genesis block has no parent messages...
	if b.Height == 0 {
		return nil, nil
	}

	// TODO: need to get the number of messages better than this
	pts, err := a.Chain.LoadTipSet(ctx, types.NewTipSetKey(b.Parents...))
	if err != nil {
		return nil, err
	}

	cm, err := a.Chain.MessagesForTipset(ctx, pts)
	if err != nil {
		return nil, err
	}

	var out []api.Message
	for _, m := range cm {
		out = append(out, api.Message{
			Cid:     m.Cid(),
			Message: m.VMMessage(),
		})
	}

	return out, nil
}

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]

Should we add a changelog entry?

[hanabi1224]

Should we add a changelog entry?

@LesnyRumcajs Changelog updated. Please re-approve if it looks good.