refactor: update r/vmc

[tenthirtyam]

In order to have a good experience with our community, we recommend that you read the contributing guidelines for making a pull request.

Summary of Pull Request

This pull request to the hcx package includes significant improvements to the VMware Cloud on AWS resource management, particularly focusing on the activation and deactivation processes. The changes enhance the reliability and maintainability of the code by introducing helper functions, improving error handling, and implementing exponential backoff for retries.

Improvements to Activation and Deactivation Processes:

• hcx/resource_vmc.go: Refactored the resourceVmcCreate, resourceVmcRead, resourceVmcUpdate, and resourceVmcDelete functions to use a new helper function authenticateAndFetchSDDC for authentication and fetching SDDC details. This change simplifies the code and reduces redundancy.
• hcx/resource_vmc.go: Introduced exponential backoff with a capped interval for retrying activation and deactivation operations, improving the robustness of these processes.
• hcx/resource_vmc.go: Enhanced error handling by providing more descriptive error messages and ensuring that appropriate diagnostics are returned.

Constants Update:

• hcx/constants/constants.go: Added a new constant VmcMaxRetryInterval to define the maximum retry interval for exponential backoff.

Code Cleanup:

• hcx/resource_vmc.go: Removed unnecessary logging and redundant code to improve readability and maintainability.

These changes collectively enhance the stability and clarity of the VMware Cloud on AWS resource management code, making it easier to maintain and extend in the future.

Type of Pull Request

• This is a bug fix.
• This is an enhancement or feature.
• This is a code style/formatting update.
• This is a documentation update.
• This is a refactoring update.
• This is a chore update
• This is something else.
  Please describe:

Related to Existing Issues

Issue Number: N/A

Test and Documentation Coverage

For bug fixes or features:

• Tests have been completed.
• Documentation has been added/updated.

Breaking Changes?

• Yes, there are breaking changes.
• No, there are no breaking changes.

[andybeltz]

A few small changes with a few thoughts...

• Have you been able to test this? and if so any functionality deltas as a large amount of the code was refactored?

[andybeltz]

LGTM