Removed recursion from commit/relocate code path

lfs_dir_commit originally relied heavily on tail-recursion, though at
least one path (through relocations) was not tail-recursive, and could
cause unbounded stack usage in extreme cases of bad blocks. (Keep in
mind even extreme cases of bad blocks should be in scope for littlefs).

In order to remove recursion from this code path, several changed were
raequired:

- The lfs_dir_compact logic had to be somewhat inverted. Instead of
  first compacting and then resolving issues such as relocations and
  orphans, the overarching lfs_dir_commit now contains a state-machine
  which after committing or compacting handles the extra changes to the
  filesystem in a single, non-recursive loop

- Instead of fixing all relocations recursively, >1 relocation requires
  defering to a full deorphan step. This step is unfortunately an
  additional n^2 process. It also required some changes to lfs_deorphan
  in order to ignore intentional orphans created as an intermediary in
  lfs_mkdir. Maybe in the future we should remove these.

- Tail recursion normally found in lfs_fs_deorphan had to be rewritten
  as a loop which restarts any time a new commit causes a relocation.
  This does show that the algorithm may not terminate, but only if every
  block is bad, which will eventually cause littlefs to run out of
  blocks to write to.