test: unit test provisioning in non-zonal regions

[tallaxes]

Description

Update unit test environment to support testing zonal and non-zonal regions. Capture and use test SKU data from eastus and westcentralus (non-zonal). Adapt existing zonal tests to run for both zonal and non-zonal environments. Add unit test of provisioning in non-zonal region.

Details

• Refactor pre-generated SKU data to support multiple regions

  • Uses map with region -> SKUs
  • Expect file per-region, with map entry populated via init()
  • Update resource SKU API fake to be region-aware and use the above

• Update the SKU generation code for the above

  • Add support for generating SKU restriction data
  • Reduce auth configuration needs (use NewDefaultAzureCredential, docs), only SUBSCRIPTION_ID is required
  • Minor fixes

• Update codegen (skugen) scripts to generate the above,

  • Generate for both eastus and westcentralus (non-zonal)
  • Remove the unnecessary auth
  • Check that subscription used is not too restrictive

• Update unit test environment and test for non-zonal

  • Add support for non-zonal test environment
  • Adapt existing zone-aware tests to run for both zonal and non-zonal regions/environments
  • Add non-zonal provisioning test

How was this change tested?

• make presubmit

Does this change impact docs?

• Yes, PR includes docs updates
• Yes, issue opened: #
• No

Release Note

[rakechill]

Basically just had some questions sprawled throughout for my own understanding. One real suggestion is to add a fake.NonZonalRegion. Overall looks good, so I'll approve