SI-8525 -Xlint:nowarn-missing-interpolator

Turn warn-missing-interpolator into an -Xlint choice. Allow choice negation with prefix "no".  Refactor choice logic from MultiString to MultiChoice. Update set of choices all together.

The mechanism between MutableSettings and concrete settings could be further over-engineered. Rube Goldberg is occupied on another project at the moment.  For instance, no easy way to override `def wildcards = choices // filter (!_.isSetByUser)`.

Depends on #3776

Review by @retronym as follow-up to #3776