Fix long paths on Windows

util::mkdirs iteratively creates each directory of a specified path. For
windows, Calling mkdir on only the drive letter or on the extended path
prefix (\?\\) will result in an error. Start after the long path prefix
and the drive letter.

This also changes AAPT2 to use AssetMaanager2 to retrieve symbols from
the symbol table. AssetManager2's zip library uses _wopen to open
windows files.

Bug:123251200
Test: aapt2_tests.exe
Change-Id: I26169d83b22d441485de3c49d63a6c4ed710e292