Release first version of Az.FrontDoor

[maddieclayton]

Description

Checklist

• I have read the Submitting Changes section of CONTRIBUTING.md
• The title of the PR is clear and informative
• The appropriate change log has been updated
• The PR does not introduce breaking changes
• If applicable, the changes made in the PR have proper test coverage
• For public API changes to cmdlets:
  • the changes have gone through a cmdlet design review (Microsoft internal partners only)
  • the cmdlet markdown files were generated using the platyPS module

[maddieclayton]

NetSign job: https://azuresdkci.westus2.cloudapp.azure.com/view/PowerShell/job/psnetsign/281/

[maddieclayton]

update sign job here: https://azuresdkci.westus2.cloudapp.azure.com/view/PowerShell/job/psnetsign/290/

[MiYanni]

I'd recommend keeping this the same as all other Az module versions, 0.5.0. If you're looking to release it for the first time, maybe make it 0.5.1 since it missed the 0.5.0 module set?
We'll have to decide a version strategy for preview modules prior to Az 1.0 release. For now, let's keep them in-line with the rest of the Az modules (what we've been doing up until now).

[maddieclayton]

We need to be super sure that we only release stable modules as "1.0.0" in December - it would be bad if all of these preview modules that are supposed to stay preview get released as stable. Fixed for the time being though.

[MiYanni]

LGTM