String Compression for ARM and ARM64

String Compression for ARM and ARM64

Changes on intrinsics and Code Generation on ARM and ARM64
for string compression feature. Currently the feature is off.

The size of boot.oat and boot.art for ARM before and after the
changes (feature OFF) are still. When the feature ON,
boot.oat increased by 0.60% and boot.art decreased by 9.38%.

Meanwhile for ARM64, size of boot.oat and boot.art before and
after changes (feature OFF) are still. When the feature ON,
boot.oat increased by 0.48% and boot.art decreased by 6.58%.

Turn feature on: runtime/mirror/string.h (kUseStringCompression = true)
runtime/asm_support.h (STRING_COMPRESSION_FEATURE 1)

Test: m -j31 test-art-target
All tests passed both when the mirror::kUseStringCompression
is ON and OFF.

Bug: 31040547
Change-Id: I24e86b99391df33ba27df747779b648c5a820649