Remove FinalizeResponseError in favor of using FinalizedError

[benalleng]

After #745 I realized we can go further and completely remove the FinalizeResponseError in favor of using FinalizedError which already has access to DirectoryResponse errors.

[spacebear21]

utACK 911154e

[coveralls]

Pull Request Test Coverage Report for Build 15619977334

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
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• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 1 of 1 (100.0%) changed or added relevant line in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.1%) to 86.035%

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Totals
Change from base Build 15619667911:	0.1%
Covered Lines:	7128
Relevant Lines:	8285

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💛 - Coveralls