Allow block cloning across encrypted datasets

[mmatuska]

Motivation and Context

When two datasets share the same master encryption key, it is safe to clone encrypted blocks. Currently only snapshots and clones of a dataset share with it the same encryption key.

Description

Allow block cloning for datasets with the same master key.

How Has This Been Tested?

TBD extending the test suite

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Performance enhancement (non-breaking change which improves efficiency)
• Code cleanup (non-breaking change which makes code smaller or more readable)
• Breaking change (fix or feature that would cause existing functionality to change)
• Library ABI change (libzfs, libzfs_core, libnvpair, libuutil and libzfsbootenv)
• Documentation (a change to man pages or other documentation)

Checklist:

• My code follows the OpenZFS code style requirements.
• I have updated the documentation accordingly.
• I have read the contributing document.
• I have added tests to cover my changes.
• I have run the ZFS Test Suite with this change applied.
• All commit messages are properly formatted and contain Signed-off-by.

[mmatuska]

@oromenahar could you please help me out with the tests here?

[oromenahar]

going to test this agains my test. Give me some time.

[oromenahar]

@mmatuska looks like this works, I'm going to update my PR with your code and force push it with a new test case. I think we can close this PR after I updated #15544

[oromenahar]

was working on something similar, you were a little bit faster than me.

[oromenahar]

I have updated my PR with your code and a new test.

[amotin]

Lets close this in favor of #15544 .