Support Kaia units

[nohkwak]

Proposed changes

• Remove submodules for conformance-test and integration-test
• Support kei, Gkei, KAIA units (Added functions : fromKei, toKei, convertFromKei, convertToKei)

Types of changes

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• Bugfix
• New feature or enhancement
• Others

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• Lint and unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
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• Any dependent changes have been merged and published in downstream modules

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[nohkwak]

I have read the CLA Document and I hereby sign the CLA