Support CodeGen for extension creation and multiple isolated virtual env

[bquantump]

Add a bunch of new features and rework parts of azdev code to engender those features:

New Setup
New features added to test
New extension create

Closes:
#208
#205
#201

[haroldrandom]

azdev test --series test_vm_image_list_by_alias would print out unnecessary mesages. Please take a look.

[bquantump]

azdev test --series test_vm_image_list_by_alias would print out unnecessary mesages. Please take a look.

(testenv) PS C:\Users\stevens\projects> azdev test --series test_vm_image_list_by_alias --discover

=============
| Run Tests |

=====================
| Discovering Tests |

'test_validators' exists in both 'cdn' and 'acs'. Resolve using cdn.test_validators or acs.test_validators
'test_cloud' exists in both 'cloud' and 'core'. Resolve using cloud.test_cloud or core.test_cloud
'test_util' exists in both 'servicefabric' and 'core'. Resolve using servicefabric.test_util or core.test_util
'test_storage_validators' exists in both 'storage' and 'core'. Resolve using storage.test_storage_validators or core.test_storage_validators

test index updated: C:\Users\stevens\projects\testenv.azdev\env_config\Users\stevens\projects\testenv/test_index\latest.json

Test on modules: test_vm_image_list_by_alias

'test_vm_image_list_by_alias' not found. If newly added, re-run with --discover
No tests selected to run.

How do I get this test?

[haroldrandom]

pls take a look the failure on Azure/azure-cli CI https://github.com/Azure/azure-cli/pull/14737/checks?check_run_id=969746791