Merge branch 'ps/object-file-wo-the-repository'

Merge branch 'ps/object-file-wo-the-repository'

Reduce implicit assumption and dependence on the_repository in the
object-file subsystem.

* ps/object-file-wo-the-repository:
  object-file: get rid of `the_repository` in index-related functions
  object-file: get rid of `the_repository` in `force_object_loose()`
  object-file: get rid of `the_repository` in `read_loose_object()`
  object-file: get rid of `the_repository` in loose object iterators
  object-file: remove declaration for `for_each_file_in_obj_subdir()`
  object-file: inline `for_each_loose_file_in_objdir_buf()`
  object-file: get rid of `the_repository` when writing objects
  odb: introduce `odb_write_object()`
  loose: write loose objects map via their source
  object-file: get rid of `the_repository` in `finalize_object_file()`
  object-file: get rid of `the_repository` in `loose_object_info()`
  object-file: get rid of `the_repository` when freshening objects
  object-file: inline `check_and_freshen()` functions
  object-file: get rid of `the_repository` in `has_loose_object()`
  object-file: stop using `the_hash_algo`
  object-file: fix -Wsign-compare warnings