Implementation of turbofan operators Word32PairShl, Word32PairShr,
Word32PairSar, Int32AddPair and Int32SubPair for MIPS.

Port of:
https://codereview.chromium.org/1765973002/
https://codereview.chromium.org/1778893004/
https://codereview.chromium.org/1778493004/
https://codereview.chromium.org/1778893005/
https://codereview.chromium.org/1842013002/

Added tests for Word32PairShr and Word32PairSar in test-run-machops.cc.

BUG=

Review URL: https://codereview.chromium.org/1819383002

Cr-Commit-Position: refs/heads/master@{#35307}