Ensure names of Quantity and other mixin columns are propagated

[mhvk]

When initializing a column from a quantity with Column(quantity) currently it is checked whether quantity.info exists and description, format, and meta are taken from it, but not the name. This fixes that.

I found this while trying to address the fact that the name of a quantity column in QTable was not propagated to the label in MRT format (see #12804). However, it turned out that was because for any mixin column, the name was not used. So, that is corrected in the second commit.

Fixes #12804

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[hamogu]

Except for @eerovaher comment (which is really nitpicky), this is good to go.