feat(hpu): Add Hpu backend implementation

This backend abstract communication with Hpu Fpga hardware.
It define it's proper entities to prevent circular dependencies with
tfhe-rs.
Object lifetime is handle through Arc<Mutex<T>> wrapper, and enforce
that all objects currently alive in Hpu Hw are also kept valid on the
host side.

It contains the second version of HPU instruction set (HIS_V2.0):
* DOp have following properties:
  + Template as first class citizen
  + Support of Immediate template
  + Direct parser and conversion between Asm/Hex
  + Replace deku (and it's associated endianess limitation) by
  + bitfield_struct and manual parsing

* IOp have following properties:
  + Support various number of Destination
  + Support various number of Sources
  + Support various number of Immediat values
  + Support of multiple bitwidth (Not implemented yet in the Fpga
    firmware)

Details could be view in `backends/tfhe-hpu-backend/Readme.md`

Cargo.toml

@@ -9,10 +9,12 @@ members = [
     "tasks",
     "tfhe-csprng",
     "backends/tfhe-cuda-backend",
+    "backends/tfhe-hpu-backend",
     "utils/tfhe-versionable",
     "utils/tfhe-versionable-derive",
     "utils/param_dedup",
     "tests",
+    "mockups/tfhe-hpu-mockup",
 ]
 
 exclude = [