Custom columns enhancements

**Issue**

- Trying to generate custom column set with all gnomAD subpopulations. Possible to do, but slow as can only seem to move column across into top slot (need to move column up to top of list, then across to the left, eg try adding gnomAD hom alt column to default columns). Currently it is faster just to add all columns than it is to add multiple columns. Also a few small otentially confusing behaviours:
- Column names are a bit confusing when you copy an existing set, e.g. I have 2 sets of my version of default columns, but I can never remember why or which is which as I can't rename them to something useful, could obviously generate a completely new set, but I'm too lazy.

- Changing the default column generates a new column set, but modifying one of my personal column sets just updates in place - again not an issue (makes sense from a tech view) but hard for new users and I'll never know the audit history of my columns.
- Small point that if I use custom columns in a template then switch accounts the custom columns are still applied (as expected), but they are labelled as default (see Qase test case VG-081)

**Describe the solution you'd like**
- Be able to move any column from available columns to my columns without having to move it up to the top of the list first.
- Be able to re-name custom column set
- (would also be cool to be able to clone column set in the table, then edit and rename-if only to be consistent with the way other tables work)
- (Would be cool to have some audit history/column version control

**Describe alternatives you've considered**
Do nothing, not that important and can be managed manually just time-consuming.