Fix missing classes in spockspace

[ncilfone]

What does this PR do?

New graph backend from #181 was causing translation from Spockspace to native python dictionary to fail in certain cases: (1) optional Enum's of @spock decorated classes, (2) nested @spock classes with definitions coming in from configuration file(s) -- as these were not getting recursed in the config check.

This PR solves both the above issues and adds additional unit tests.

Checklist

• [x] Did you adhere to PEP-8 standards?
• [x] Did you run black and isort prior to submitting your PR?
• [x] Does your PR pass all existing unit tests?
• [x] Did you add associated unit tests for any additional functionality?
• [x] Did you provide documentation (Google Docstring format) whenever possible, even for simple functions or classes?

[coveralls]

Pull Request Test Coverage Report for Build 1679181498

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.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 13 of 13 (100.0%) changed or added relevant lines in 3 files are covered.
• 3 unchanged lines in 1 file lost coverage.
• Overall coverage increased (+0.03%) to 95.056%

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Files with Coverage Reduction	New Missed Lines	%
spock/backend/field_handlers.py	3	92.36%
<!--	Total:	3		-->

Totals
Change from base Build 1650853062:	0.03%
Covered Lines:	1615
Relevant Lines:	1699

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💛 - Coveralls