Fix for domain join error if domain join user account is already in Administrators group

[SvenAelterman]

Overview/Summary

Closes #727
Closes #729

This PR fixes/adds/changes/removes

1. Checks if the domain join user account is already in the local Administrators group before attempting to add.
2. Some typos are fixed.

Breaking Changes

N/A

Testing Evidence

N/A

As part of this Pull Request I have

• Read the Contribution Guide and ensured this PR is compliant with the guide
• Ensured the resource API versions in .bicep file/s I am adding/editing are using the latest API version possible
• Checked for duplicate Pull Requests
• Associated it with relevant GitHub Issues
• (AVD LZA Team Only) Associated it with relevant ADO Items
• Ensured my code/branch is up-to-date with the latest changes in the main branch
• Performed testing and provided evidence.
• Updated relevant and associated documentation (e.g. Contribution Guide, Module READMEs, Docs etc.)

[SvenAelterman]

Working in also fixing #729

[SvenAelterman]

Closes #729 also.

I observed errors deleting the zip file and the simple fix of deleting the nested zip file seems to have resolved it. I am unsure why it would matter though.