Moves reductions to a new tile id group sub-directory

[havok2063]

This PR updates the DRP to output reductions to a new tile ID group sub-directory. This is to make the SAS file structure more navigable. Tiles are now nested into integer groups, e.g. 1055XX, similar to other SDSS systems.

For those exposures with no tile id, I have also changed the default tile from 1111 to 11111. I've changed it in most places, except the notebook files.

Example structure will now look like, at $LVM_SPECTRO_REDUX:

• master
  • 1055XX/
    • 1055360/
      • 60269/
    • 1055604/
      • 60269/
  • 0011XX/
    • 11111/

This requires changes to the tree and sdss_access products. Marking this draft until PRs are in place for those. See sdss/tree#77 and sdss/sdss_access#49