feat: New Consistency group Samples : Add Disk, List Disks, Remove Disk

[Thoughtseize1]

Description

New Consistency Group Samples for doc.page :

Region tag	Filename
compute_consistency_group_add_disk	add_disk_consistency_group.py
compute_consistency_group_disks_list	list_disks_consistency_group.py
compute_consistency_group_remove_disk	remove_disk_consistency_group.py

Checklist

• I have followed Sample Guidelines from AUTHORING_GUIDE.MD
• README is updated to include all relevant information
• Tests pass: nox -s py-3.9 (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)
• This sample adds a new sample directory, and I updated the CODEOWNERS file with the codeowners for this sample
• This sample adds a new Product API, and I updated the Blunderbuss issue/PR auto-assigner with the codeowners for this sample
• Please merge this PR for me once it is approved

[m-strzelczyk]

I'm wondering if replacing the disk_region_flag with disk_region_flag = disk_location[-1].isdigit() would make the sample more readable or easier to use? I personally always like when the code I want to use is able to automatically detect what kind of values I pass.

On the other hand, that is less explicit and introduces a very slight chance that the code will fail one day, if Google decides to change the region and zone naming schema.

What do you think?

[Thoughtseize1]

Thank you for your thoughts. I'm quite certain that if Google ever decides to change the naming policy for regions and zones, this code will break. In fact, I imagine many things would need fixing if such a change happens! 😅😬 But will it happen anytime soon? I don't think so :)

I also appreciate when code takes care of things for me automatically. Requiring users to explicitly set a disk_region_flag could lead to more errors on their part.
So, I'll make adjustments to the sample by modifying the disk creation and removing logic to make these functions more user-friendly 🙌