Move libfiemap_writer from fs_mgr to gsid.

The only consumer of this library is gsid. This CL moves it from fs_mgr.
The code is identical with one exception: the namespace and library have
been renamed to "libfiemap".

Bug: 134536978
Test: gsid, fiemap_writer_test build
Change-Id: I2eb3c5224a92c49b36bcc816306b40cc2c79a001
21 files changed