ufs2: Add rewind_dir functionality

Change-Id: I7033273d02131b38cf3de0632058710c5d2ff36c
Reviewed-on: https://review.haiku-os.org/c/haiku/+/6855
Reviewed-by: waddlesplash <waddlesplash@gmail.com>

ufs2: Fix wrong lookup iteration

Passed size needs to be size of name buffer, not of length we compare to.
Fix the value and remove now unused parameter.

Change-Id: Idb69a0e78ba376751edf8b3df3635cd0af4c9460
Reviewed-on: https://review.haiku-os.org/c/haiku/+/6850
Reviewed-by: Adrien Destugues <pulkomandy@pulkomandy.tk>

ufs2: All directories are read sucessfully.

Change-Id: I87d3d77d48396ecd0e8fa649169f6e899d161f66
Reviewed-on: https://review.haiku-os.org/c/haiku/+/3028
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>

ufs2: implementing open_dir and read_dir function

Root directory is read sucessfully.

Change-Id: I8bdc8c1a52edb679a6cb4b5f70e7f42eb2b2c8f1
Reviewed-on: https://review.haiku-os.org/c/haiku/+/2907
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>