fix(IAM Identity): add PowerVS compute resource type support

[briangleeson]

PR summary

This PR replaces and fixes this previous PR: IBM/platform-services-java-sdk#302

• Add support for PowerVS compute resource type
• Fix issue with value_string in Identity Preference handling by making it not required
• Fix issue from previous PR with email strings

PR Checklist

Please make sure that your PR fulfills the following requirements:

• The commit message follows the Angular Commit Message Guidelines.
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

Does this PR introduce a breaking change?

• Yes
• No

Other information

$ npm run test-integration

PASS  test/integration/iam-identity.v1.test.js (813.888 s)

Test Suites: 1 passed, 1 total
Tests:       78 passed, 78 total
Snapshots:   0 total
Time:        814.785 s
Ran all test suites matching /test\\integration\\iam-identity/i.


$ npm run test-examples

PASS  examples/iam-identity.v1.test.js (739.571 s)

Test Suites: 1 passed, 1 total
Tests:       58 passed, 58 total
Snapshots:   0 total
Time:        742.255 s, estimated 750 s
Ran all test suites matching /examples\\iam-identity/i.

[CLAassistant]

All committers have signed the CLA.

[pyrooka]

Looks good!

[ibm-devx-sdk]

🎉 This PR is included in version 0.83.5 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

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