Update servers improvements

[dylan-way]

Proposed changes

Update UpdateHTTPServers and UpdateStreamServers:

• No longer make extra GET requests for each PUT and DELETE request.
• Removes identical duplicate servers.
• Returns errors for duplicate servers with different parameters.

Adds Content-Type header to NGINX client PATCH requests.

Checklist

Before creating a PR, run through this checklist and mark each as complete.

• I have read the CONTRIBUTING doc
• I have added tests that prove my fix is effective or that my feature works
• I have checked that all unit tests pass after adding my changes
• I have updated necessary documentation
• I have rebased my branch onto main
• I will ensure my PR is targeting the main branch and pulling from my branch from my own fork

[nginx-bot]

Hi @dylan-way! Welcome to the project! 🎉

Thanks for opening this pull request!
Be sure to check out our Contributing Guidelines while you wait for someone on the team to review this.

[github-actions]

✅ All required contributors have signed the F5 CLA for this PR. Thank you!
_{Posted by the CLA Assistant Lite bot.}

[dylan-way]

I have hereby read the F5 CLA and agree to its terms