bindgen cli/v6

[jasonish]

• rust: integrate bindgen to generate rust bindings to C
  Add a minimal integration of bindgen to the build.

  This required some refactoring of the C so app-layer-events.h did not
  also include "rust.h", which causes issues for bindgen, probably
  related to circular references.

  AppLayerEventType was chosen as the first step as its an argument type
  some app-layer functions that we may want to use bindgen to export
  Rust, and one of the requirements of bindgen might be that C functions
  should only use datatypes defined in C, and not Rust. Following such a
  rule also prevents circular dependencies between Rust and C code.

  As bindgen can only accept one header file, we construct a
  pseudo-header file of all the headers that need to be
  consumed. Makefile dependency checking is done to make sure the
  pseudo-header is only generated as needed to avoid rebuilding every
  time.

  Special handling is required for Windows to use the Windows path.

  Ticket: http: configures libhtp to allow spaces in uri OISF/suricata#7341

• bindgen: pre-generate rust bindings to C
  This simplifies building, as we don't have to worry about path and
  such under autoconf/automake. It does however mean when we update C
  headers that are exposed to Rust, we manually have to re-generate the
  bindings, but this is a check we can do in CI.

  It also eliminates the need for everyone who wants to build Suricata
  to have bindgen and clang tools installed.

• app-layer: rename AppLayerEventType to SCAppLayerEventType
  Follow the naming scheme for public exports.

• app-layer: remove prototypes from decode.h
  This lets us remove decode.h from app-layer-events.h as pulling in
  app-layer-events.h shouldn't result in pulling in dpdk, and other
  includes not related to app-layer-events.

  decode.h also doesn't need those forward declarations anymore due to
  previous changes.

• bindgen: export SCAppLayerStateGetEventInfoByIdFn from C to Rust
  Instead of defining this function pointer in type in Rust, and having
  it in C signatures, create a type and export it to Rust.

  To facilitate this, and new header has been creates,
  "app-layer-types.h", this is to avoid the circular reference of C
  headers pulling in "rust.h" which are required to generate Rust
  bindings.

• bindgen: export AppProto and AppProtoEnum to Rust
  This exposes the C define ALPROTO values to Rust without having to
  perform some runtime initialization with init_ffi.

  As app-layer-protos.h was clean of a circular reference to rust.h we
  could use it directly, it just needed the addition of
  suricata-common.h.

• dhcp: use ALPROTO_DHCP from bindgen

• github-ci: test if bindgen bindings are up to date
  This required us to remove the auto-generated by header as it can
  change depending on what version is used.

  I suppose different versions could generate slightly different output
  that would cause this error out. In which case we may want to use a
  custom script that can be a bit smarter output, or simply error out if
  any of the headers used in the bindings is newer than the generated
  _sys.rs file.

• rust: add bindgen bindings check to make check
  If we have bindgen, and we're building in-tree, rebuild the bindings
  and compare to the previous bindings and print a warning if there is a
  difference.

  Only a warning for now, as I'm not sure where this might fail, and I
  don't want it to become a nuisance.