az_cli_universal_dependency: Enhance error messaging

[makubacki]

1. If the azure-devops extension is not installed, provide a URL with installation instructions. This link can directly be clicked in many shell environments.
2. If an error occurs running the Azure CLI then show the error message to the user. This often has helpful instructions for what needs to be done to resolve the error. Example shown below.

Before:

    raise Exception("{0} failed with Return Code: {1}".format(cmd, returncode_str))
	Exception: az artifacts universal download --organization https://dev.azure.com/Organization/
	  --feed FEED --name NAME --version 0.0.1 --path "PATH" failed with Return Code: 0x00000001

After:

    raise Exception(
      Exception:
        Command "az artifacts universal download --organization https://dev.azure.com/Organization/
	      --feed FEED --name NAME --version 0.0.1 --path "PATH"" failed with 1.

      ERROR: Failed to update Universal Packages tooling.
        Before you can run Azure DevOps commands, you need to run the login command(az login if using
		AAD/MSA identity else az devops login if using PAT token) to setup credentials.
		Please see https://aka.ms/azure-devops-cli-auth for more information.

[codecov]

Codecov Report

Attention: Patch coverage is 80.00000% with 1 line in your changes missing coverage. Please review.

Project coverage is 79.49%. Comparing base (bf643b0) to head (e050c66).
Report is 129 commits behind head on master.

Files with missing lines	Patch %	Lines
...ronment/extdeptypes/az_cli_universal_dependency.py	80.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #934      +/-   ##
==========================================
+ Coverage   78.75%   79.49%   +0.74%     
==========================================
  Files          49       41       -8     
  Lines        4909     5058     +149     
==========================================
+ Hits         3866     4021     +155     
+ Misses       1043     1037       -6     

Files with missing lines	Coverage Δ
...ronment/extdeptypes/az_cli_universal_dependency.py	72.47% <80.00%> (+28.99%)	⬆️

... and 48 files with indirect coverage changes

[makubacki]

@Javagedes, pushed the fix for the earlier unit test failure.