[MachineCombiner] Support local strategy for traces

For in-order cores MachineCombiner makes better decisions when the critical path
is calculated only for the current basic block and does not take into account
other blocks from the trace.

This patch adds a virtual method to TargetInstrInfo to allow each target decide
which strategy to use.

Depends on D140541

Reviewed By: spatel

Differential Revision: https://reviews.llvm.org/D140542