This change moves the definition of the bits stored in DebugInfo::flags
to Torque, and updates the only Torque usage of that field to use more
natural syntax. This is intended as an example of common patterns found
in various other classes. Several supporting changes are required:

1. Add a new type representing a bitfield struct stored within a Smi. It
   is currently called SmiTagged, but I'm open to suggestions.
2. Add an enum-style output for Torque bitfield structs whose bitfields
   occupy only one bit each.
3. Add a new case to MachineOperatorReducer that makes the generated
   code for IncBlockCounter match with what was generated before this
   change.
4. Add support for reporting these bitfields in the postmortem debugging
   API. The format matches existing bitfields but with an offset value
   that includes the SMI shift size.

Bug: v8:7793
Change-Id: Icaecbe4a162da55d2d9a3a35a8ea85b285b2f1b7
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2028832
Commit-Queue: Seth Brenith <seth.brenith@microsoft.com>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
Cr-Commit-Position: refs/heads/master@{#66182}