[IMPROVEMENT] Add global setting for enable v1 or v2 volume support

[derekbit]

Is your improvement request related to a feature? Please describe (👍 if you like this request)

Add global setting for enable v1 or v2 volume support.

Describe the solution you'd like

Describe alternatives you've considered

Additional context

[longhorn-io-github-bot]

Pre Ready-For-Testing Checklist

• Where is the reproduce steps/test steps documented?
  The reproduce steps/test steps are at:

• v1-data-engine

  1. Create a LH cluster
  2. Create a v1 volume and attacg it
  3. Set v1-data-engine setting to false. The request should be rejected.
  4. Detach the volume. Then, set v1-data-engine setting to true. The request should be accepted.
  5. Try to attach the volume. The attachment should not work.
  6. Set v1-data-engine setting to true. Then, attach the volume again, it should work.

• v2-data-engine

  • Similar steps as v1-data-engine

• Does the PR include the explanation for the fix or the feature?

• Does the PR include deployment change (YAML/Chart)? If so, where are the PRs for both YAML file and Chart?
  The PR for the YAML change is at:
  The PR for the chart change is at:

#7403

• Have the backend code been merged (Manager, Engine, Instance Manager, BackupStore etc) (including backport-needed/*)?
  The PR is at

longhorn/longhorn-manager#2386

• Which areas/issues this PR might have potential impacts on?
  Area: v1 and v2 volumes, instance-managers
  Issues

[yangchiu]

Verified passed on master-head (longhorn-manager be08850) following the test steps.