Auto merge of #43015 - arielb1:every-error-counts, r=eddyb

Auto merge of #43015 - arielb1:every-error-counts, r=eddyb

report the total number of errors on compilation failure

Prior to this PR, when we aborted because a "critical pass" failed, we displayed the number of errors from that critical pass. While that's the number of errors that caused compilation to abort in *that place*, that's not what people really want to know. Instead, always report the total number of errors, and don't bother to track the number of errors from the last pass that failed.

This changes the compiler driver API to handle errors more smoothly, therefore is a compiler-api-[breaking-change].

Fixes #42793.

r? @eddyb