Support sparsity in FdFile::Copy

Output a sparse file during FdFile::Copy by reading and checking each
block of the source file in userspace, writing only the non-zero blocks
and skipping over any zeroed blocks (holes). This helps to save disk
space on file systems that support sparse files.

The current target use-case is odrefresh on Android U and earlier, where
sparse staging files which are copied to an installation directory must
remain sparse.

The implementation and tests are based on and replace a reverted lseek
SEEK_DATA/SEEK_HOLE based sparse file copy (7e06898) following observed
issues with lseek SEEK_DATA on f2fs, where lseek SEEK_DATA will
sometimes return an incorrect offset. This bug is not yet able to be
reproduced in the gtests, but can be reproduced with a manual odrefresh
invocation.

The implementation support and tests are refactored over that of 7e06898:

* Add tests for partial sparse-file copying, and that sparsity is
  impacted as expected according to the copy alignment.

* Only dissallow copies to non-empty files if the existing data is in
  the target copy region, and add a test case.

Bug: 323906594

Tested on oriole and shiba (ext4 and f2fs):
Test: dex2oat ... -g --strip -oat-symbols=...
Test: odrefresh --force-compile
Test: art/tools/run-gtests.sh

Co-authored-by: Richard Neill <richard.neill@arm.com>
Co-authored-by: Ruben Ayrapetyan <ruben.ayrapetyan@arm.com>
Change-Id: Idcc5a9c5320b3a80ea5c6186fa4c41d92f1727f8

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