For usecases that needed more than 64bits we were using
std::bitset container. This has slower perf compared to
the BitSetT container.

Add a new class that can support large bitsets by wrapping
an array of BitSet32/BitSet64 objects, depending on CPU
bitness, as the container.

Bug: angleproject:3877
Tests: angle_unittests.exe --gtest_filter=BitSetArrayTest*
       angle_white_box_perftests.exe --gtest_filter=BitSetIteratorPerfTest*
Change-Id: I3f4a635f9e6974a99db7a4b592ab206aad754760
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2664733
Commit-Queue: Mohan Maiya <m.maiya@samsung.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>