fix(IAM Policy Management): remove `options` property from PolicyAssignment

[siddhuvarma1997]

PR summary

PR Checklist

Please make sure that your PR fulfills the following requirements:

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

Current vs new behavior

Does this PR introduce a breaking change?

• [ ] Yes
• [x] No

Other information

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[siddhuvarma1997]

Issue: https://github.ibm.com/IAM/AM-issues/issues/2361

unit tests:

Integration tests:

example tests:

[ibm-devx-sdk]

:tada: This PR is included in version 0.64.3 :tada:

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