libfiemap: Create/Open returns FiemapStatus

Add variants to SplitFiemap::Create and FiemapWriter::Open that
returns a FiemapStatus and take a unique_ptr<T>* out parameter to
get more information on the reason of the failure.

Test: fiemap_writer_test
Test: fiemap_image_test
Bug: 138808058
Change-Id: Iea77ac9810f98c2202e038b7aede15dd2d137b2b