## Summary
Right now, if we have two fixes that have an overlapping edit, but not
an _identical_ set of edits, they'll conflict, causing us to do another
linter traversal. Here, I've enabled the fixer to support partially
overlapping edits, which (as an example) let's us greatly reduce the
number of iterations required in the test suite.
The most common case here is that in which a bunch of edits need to
import some symbol, and then use that symbol, but in different ways. In
that case, all edits will have a common fix (to import the symbol), but
deviate in some way. With this change, we can do all of those edits in
one pass.
Note that the simplest way to enable this was to store sorted edits on
`Fix`. We don't allow modifying the edits on `Fix` once it's
constructed, so this is an easy change, and allows us to avoid a bunch
of clones and traversals later on.
Closes#5800.
