Allow ActiveRecord::Base#pluck to accept hash values

[fatkodima]

Follow up to #45612 and #50000.

# Before
Post.joins(:comments).pluck("posts.id", "comments.id", "comments.body")

# After
Post.joins(:comments).pluck(posts: [:id], comments: [:id, :body])

The same applies to .pick, which is implemented using .pluck.