Improve auth CLI missing error

[danielrbradley]

Add context for why the CLI is expected and what operation is being attempted.

Fixes #3347

This will now print a message like:

Diagnostics:
  azure-native:features:SubscriptionFeatureRegistration (subscriptionFeatureRegistration):
    error: checking az cli version: could not find `az`: exec: "az": executable file not found in $PATH: MSI, OIDC, 
      client secret and client certificate authentication are not configured so we require the AZ CLI for authentication

[github-actions]

Does the PR have any schema changes?

Looking good! No breaking changes found.
No new resources/functions.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.

Project coverage is 56.82%. Comparing base (2c7da0a) to head (944884d).
Report is 1 commits behind head on master.

Files	Patch %	Lines
provider/pkg/provider/auth.go	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3349      +/-   ##
==========================================
- Coverage   56.82%   56.82%   -0.01%     
==========================================
  Files          66       66              
  Lines        8082     8083       +1     
==========================================
  Hits         4593     4593              
- Misses       3054     3055       +1     
  Partials      435      435              

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[thomas11]

The message is missing a period, semicolon or the like after $PATH. I know the linter says not to use full sentences in errors, but maybe we should here?

[danielrbradley]

The message is missing a period, semicolon or the like after $PATH. I know the linter says not to use full sentences in errors, but maybe we should here?

Oh that was just me mocking up the diagnostics. It actually has a colon between. Updated the example.

[mikhailshilkov]

AZ CLI

It's called Azure CLI in all official product docs. If you mean the command, then it's probably lowercase az.