feat(rpc): add StateMinerInitialPledgeForSector method

[virajbhartiya]

Summary of changes

Changes introduced in this pull request:

• Implements StateMinerInitialPledgeForSector

Reference issue to close (if applicable)

Closes #4907

Other information and links

Change checklist

• I have performed a self-review of my own code,
• I have made corresponding changes to the documentation. All new code adheres to the team's documentation standards,
• 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.

[elmattic]

I don't see the different checks that Lotus is doing:

	if sectorDuration <= 0 {
		return types.EmptyInt, xerrors.Errorf("sector duration must greater than 0")
	}
	if sectorSize == 0 {
		return types.EmptyInt, xerrors.Errorf("sector size must be non-zero")
	}
	if verifiedSize > uint64(sectorSize) {
		return types.EmptyInt, xerrors.Errorf("verified size must be less than or equal to sector size")
	}

Don't we need them?

[virajbhartiya]

@elmattic added these checks

[elmattic]

lgtm. Just a lint error to fix for the CI to pass successfully.

[virajbhartiya]

@lemmih can you please take a look once

[elmattic]

) -> Result<(ChainEpoch, u64), anyhow::Error> { 
                                               ^
                                               |
 There is a trailing space here, please enable format on save in your editor