Consolidate Constants

Description

This PR consolidates constants, and does other refactorings for code organization.

Test Policy Compliance

[x] I have added or updated unit tests for my changes.
[x] I have included integration tests where applicable.
[x] All new and existing tests pass successfully.

Code Quality

[x] I have followed the coding standards for this project.
[x] I have performed a self-review of my code.
[x] My code is well-commented, particularly in areas that may be difficult to understand.

Documentation

[x] I have made corresponding changes to the documentation (if applicable).
[x] I have updated any relevant READMEs or wiki pages.

Additional Comments

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Checklist

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[x] You have read the contributing guidelines and especially the test policy.
[x] You have thoroughly tested your changes.
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vmware-tanzu / secrets-manager

Consolidate Constants #1009