ENH: Add duplicated to MaskedArray/ExtensionArray interface

[phofl]

Feature Type

• Adding new functionality to pandas

• Changing existing functionality in pandas

• Removing existing functionality in pandas

Problem Description

#48150 will support masks in the duplicated hashtable function. Currently, we have to special case MaskedArrays to pass the mask only when necessary into the function. This could be avoided when adding duplicated to the interface, same as unique is currently implemented

Feature Description

See above

Alternative Solutions

See above

Additional Context

No response

cc @mroeschke @jorisvandenbossche

[tehunter]

take

[phofl]

This needs some discussion first

[tehunter]

No problem! I'm giving it a attempt on my personal fork to get more familiar with the ExtensionArray code base, but won't push through any PRs until there's a consensus on discussion items.

[jbrockmendel]

duplicate of #27264?