[Modules] Adds zoneRedundant property to serverfarms module

[DanielLarsenNZ]

Description

Adds zoneRedundant property to Microsoft.Web/serverfarms module.

Partially fixes #1105.

Type of Change

Please delete options that are not relevant.

• New feature (non-breaking change which adds functionality)
• Update to documentation

Checklist

• I'm sure there are no other open Pull Requests for the same update/change
• My corresponding pipelines / checks run clean and green without any errors or warnings
• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (readme)
• I did format my code

[DanielLarsenNZ]

@senavar I see you have #1105 in progress on the Backlog. Let me know if this helps with that.

[AlexanderSehr]

Much appreciated @DanielLarsenNZ , thank you