Rearranged tag encodings to make space for BECKSUM, ORPHAN, etc

Also:

- Renamed GSTATE -> GDELTA for gdelta tags. GSTATE tags added as
  separate in-device flags. The GSTATE tags were already serving
  this dual purpose.

- Renamed BSHRUB* -> SHRUB when the tag is not necessarily operating
  on a file bshrub.

- Renamed TRUNK -> BSHRUB

The tag encoding space now has a couple funky holes:

- 0x0005 - Hole for aligning config tags.

  I guess this could be used for OCOMPATFLAGS in the future?

- 0x0203 - Hole so that ORPHAN can be a 1-bit difference from REG. This
  could be after BOOKMARK, but having a bit to differentiate littlefs
  specific file types (BOOKMARK, ORPHAN) from normal file types (REG,
  DIR) is nice.

  I guess this could be used for SYMLINK if we ever want symlinks in the
  future?

- 0x0314-0x0318 - Hole so that the mdir related tags (MROOT, MDIR,
  MTREE) are nicely aligned.

  This is probably a good place for file-related tags to go in the
  future (BECKSUM, CID, COMPR), but we only have two slots, so will
  probably run out pretty quickly.

- 0x3028 - Hole so that all btree related tags (BTREE, BRANCH, MTREE)
  share a common lower bit-pattern.

  I guess this could be used for MSHRUB if we ever want mshrubs in the
  future?

lfs.h

@@ -116,11 +116,11 @@ enum lfs_error {
 // File types
 enum lfs_type {
     // file types
-    LFS_TYPE_REG            = 2,
-    LFS_TYPE_DIR            = 3,
+    LFS_TYPE_REG            = 1,
+    LFS_TYPE_DIR            = 2,
 
     // used internally, don't use this
-    LFS_TYPE_INTERNAL       = 4,
+    LFS_TYPE_INTERNAL       = 3,
 
 //    // internally used types
 //    LFS_TYPE_SPLICE         = 0x400,