Better implementation of inline files, now with overflowing

Now when a file overflows the max inline file size, it will be correctly
written out to a proper block. Additionally, tweaked corner cases around
inline file, however this still needs significant testing.

A real neat part that surprised me is that littlefs _already_ contains
the logic for writing out inline files: in lfs_file_relocate! With a bit
of tweaking, littlefs can pull off both the overflow from inline to
normal files _and_ the relocating of bad blocks in files with the same
piece of logic.

tests/test_dirs.sh

@@ -357,7 +357,7 @@ tests/test.py << TEST
 TEST
 
 echo "--- Multi-block directory with files ---"
-tests/test.py -s << TEST
+tests/test.py << TEST
     lfs_mount(&lfs, &cfg) => 0;
     lfs_mkdir(&lfs, "prickly-pear") => 0;
     for (int i = 0; i < $LARGESIZE; i++) {