[WIP][CodeCompletion] Only filter solutions based on number of fixes

[ahoppen]

The current score filtering rule for filtering code completion solutions based on their score are as follows:

• Inside a component step, perform score filtering just like for normal type checking. That is, only keep the solutions with the lowest scores
• After finding solutions, we keep all solutions that have no fixes associated with them. If solutions do have fixes, we only keep those with the lowest score

This scoring behavior is fragile because of several reasons:

• If the expression containing the code completion token is moved to a component step, we only receive the best solution and thus miss code completion suggestions. These implementation details shouldn’t affect code completion behavior.
• Modifying the expression the completion happens in to contain a fix in all solutions (e.g. by having a function argument whose type doesn’t match), causes us to only consider the best solution. I code completion behavior should be stable against these kinds of changes.

I propose that in the entire pipeline, we only filter solutions based on the number of fixes and ignore all other score kinds.

The main thing to make sure, is that this doesn’t affect performance like it did in #35535.

rdar://83435965

[ahoppen]

@swift-ci Please SourceKit stress test

[ahoppen]

@swift-ci Please SourceKit stress test

[ahoppen]

@swift-ci Please smoke test

[shahmishal]

@swift-ci Please SourceKit stress test

[ahoppen]

Closing because this has the same performance problems as the original PR. We need more targeted fixes to avoid filtering out relevant solutions during code completion.