refactor: use time MS in gas fee calcs

[alarso16]

Why this should be merged

Roughly syncs ava-labs/coreth#1288 and ava-labs/coreth#1329, just to maintain identical structure throughout the repo.

How this works

Same changes, except for the ACP-176 one. This is NOT a cherry-pick, since every line would have conflicted due to the feeConfig.

How this was tested

Existing UT.

Need to be documented?

No

Need to update RELEASES.md?

No

[michaelkaplan13]

Confirmed that:

• all of the changes in the original coreth PR that are relevant to subnet-evm are included.
• subnet-evm specific changes, particularly in gas_limit.go (due to still using the windower mechanism) appear correct.

[ceyonur]

just a small comment, mostly lgtm

[alarso16]

upon @ceyonur's recommendation, added EstimateNextBaseFee to this PR

[michaelkaplan13]

In the future, I strongly prefer keeping sync PRs 1 to 1 for the sake of reviewers. It may leave some PRs in an intermediate state individually, but they're must easier to compare and ensure all of the intended changes are included properly.

That being said, I was able to review the individual commit and this LGTM, there is just one place I commented that we may have missed in coreth.

[ceyonur]

In the future, I strongly prefer keeping sync PRs 1 to 1 for the sake of reviewers. It may leave some PRs in an intermediate state individually, but they're must easier to compare and ensure all of the intended changes are included properly.

That being said, I was able to review the individual commit and this LGTM, there is just one place I commented that we may have missed in coreth.

I agree, I forgot that those changes were in another PR.

[ceyonur]

there is another place to be changed