Add Workspace provisioning using Channel API examples

[aihgii]

Description

Fixes #5583

This sample uses Cloud Channel API.

Several new variables were added to testing/test-env.tmpl.sh with CHANNEL prefix.

Checklist

• I have followed Sample Guidelines from AUTHORING_GUIDE.MD
• README is updated to include all relevant information
• Tests pass: nox -s py-3.6 (see Test Environment Setup)
• Lint pass: nox -s lint (see Test Environment Setup)
• These samples need a new API enabled in testing projects to pass (let us know which ones)
• These samples need a new/updated env vars in testing projects set to pass (let us know which ones)
• Please merge this PR for me once it is approved.
• This sample adds a new sample directory, and I updated the CODEOWNERS file with the codeowners for this sample

[snippet-bot]

Here is the summary of changes.

You are about to add 10 region tags.

• channel/workspace/provisioning/create_entitlement.py:46, tag channel_get_admin_sdk_customer_id
• channel/workspace/provisioning/create_entitlement.py:64, tag channel_create_client
• channel/workspace/provisioning/create_entitlement.py:86, tag channel_select_offer
• channel/workspace/provisioning/create_entitlement.py:116, tag channel_check_exists
• channel/workspace/provisioning/create_entitlement.py:139, tag channel_create_customer
• channel/workspace/provisioning/create_entitlement.py:161, tag channel_provision_cloud_identity
• channel/workspace/provisioning/create_entitlement.py:195, tag channel_create_entitlement
• channel/workspace/provisioning/create_entitlement.py:246, tag channel_suspend_entitlement
• channel/workspace/provisioning/create_entitlement.py:271, tag channel_transfer_entitlement
• channel/workspace/provisioning/create_entitlement.py:295, tag channel_delete_customer

---

This comment is generated by snippet-bot.
If you find problems with this result, please file an issue at:
https://github.com/googleapis/repo-automation-bots/issues.
To update this comment, add snippet-bot:force-run label or use the checkbox below:

• Refresh this comment

[engelke]

Please create a separate PR for the CODEOWNERS change so that the new code owner can be assigned to review this PR on that's merged.

[tmatsuo]

@aihgii

The snippet-bot will be happy when you use region tags with channel_ prefix. Also, maybe you should use underscore and lowercase for python samples. Most of the python samples are using that style.

For example, channel_get_admin_sdk_customer_id instead of getAdminSDKCustomerId, etc etc.

[aihgii]

@tmatsuo

Updated, please review.

[tmatsuo]

I'm afraid that these asserts may pass even when some of the API call returns unexpected results?

[tmatsuo]

Do we need to add these values to our secret in secret manager for CI builds on Kokoro?

[parthea]

Hi @aihgii, I'm going to close this PR as the linked issue is closed but please feel free to re-open it.