This patch adds micro-benchmarks for TypedArray#join with and without a separator.
The benchmark can be used to measure any TypedArray#join optimizations we implement in the future.

Test:

  tools/run_perf.py --binary-override-path=out/x64.release/d8 \
    --filter JSTests/TypedArrays/Join \
    test/js-perf-test/JSTests.json

Bug: v8:7624
Change-Id: I526af50da0eff400d21b807ba30a9de2c3d87476
Reviewed-on: https://chromium-review.googlesource.com/c/1369333Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Sergiy Belozorov <sergiyb@chromium.org>
Commit-Queue: Peter Wong <peter.wm.wong@gmail.com>
Cr-Commit-Position: refs/heads/master@{#58163}