User defined column remapping

* Fix #5488 by adding optional className prop to AccordianList sections

* add conditional icon for saved questions

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External remappings are only supported on drivers that have foreign
keys. A new test was added to for ordering by the remapped but it
wasn't narrowed to only engines that support foreign keys. This commit
fixes that text.

* preserve collection_id in overwrite mode

* add test

add email troubleshooting guide to docs

If a field is set to an enum or category type and has a remapping,
that should be cleared if the field moves to a special_type that is
not allowed to have remappings (i.e. text). This commit adds checks
for that and clears the dimension in that case.

If a field is set to an enum or category type and has a remapping,
that should be cleared if the field moves to a special_type that is
not allowed to have remappings (i.e. text). This commit adds checks
for that and clears the dimension in that case.

The previous commit fixed a bug when there is no order by, but there
is a remapping. The corresponding change to the
add-dimmension-projections-test didn't happen. This fixes that test failure.

When ordery-by was nil, it was using in a mapv intended to replace
remapped values with what they have been remapped to. This cause
failures in the query_processor as nil was expected there, not an
empty list.

When an MBQL query has an order by for a column that has been
remapped via FK, it will swap the order by for the original field for
the remapped field. Previously this would order by the original source
column and apply that to the remapping which would be unexpected.

Fix 3613

Use the JSON encoders for XLSX objects with no encoders

If we have an external remapping, human_readable_field_id is
required. We now return a 400 if that is missing.

Currently this is used similarly to category. As we get more remapping
features (booleans, strings etc) this will be different from
categories and won't have the existing category baggage.

One of the tests added recently changes the special_type of
category_id. It should have save what it's original value was and
restored it after it was done instead of assuming it's previous value
was nil.