Hexagon (target/hexagon) Use QEMU decodetree (32-bit instructions)

Hexagon (target/hexagon) Use QEMU decodetree (32-bit instructions)

The Decodetree Specification can be found here
https://www.qemu.org/docs/master/devel/decodetree.html

Covers all 32-bit instructions, including HVX

We generate separate decoders for each instruction class.  The reason
will be more apparent in the next patch in this series.

We add 2 new scripts
    gen_decodetree.py        Generate the input to decodetree.py
    gen_trans_funcs.py       Generate the trans_* functions used by the
                             output of decodetree.py

Since the functions generated by decodetree.py take DisasContext * as an
argument, we add the argument to a couple of functions that didn't need
it previously.  We also set the insn field in DisasContext during decode
because it is used by the trans_* functions.

There is a g_assert_not_reached() in decode_insns() in decode.c to
verify we never try to use the old decoder on 32-bit instructions

Signed-off-by: Taylor Simpson <ltaylorsimpson@gmail.com>
Reviewed-by: Brian Cain <bcain@quicinc.com>
Message-Id: <20240115221443.365287-2-ltaylorsimpson@gmail.com>
Signed-off-by: Brian Cain <bcain@quicinc.com>