V extension general framework and configuration setting instructions (#191)

* V extension general framework and configuration setting instructions

* Update model/riscv_insts_vext_utils.sail

fix a typo

Co-authored-by: Nicolas Brunie <nibrunie@gmail.com>
Signed-off-by: BrighterW <xinlai.w@rioslab.org>

* Update model/riscv_insts_vext_vset.sail

* Revisions after Nov 22 meeting

* Update effect matching for functions in riscv_vlen.sail

* Fix code formatting issues

* Update model/riscv_insts_vext_utils.sail

Co-authored-by: Jessica Clarke <jrtc27@jrtc27.com>
Signed-off-by: Xinlai Wan <xinlai.w@rioslab.org>

* Fix coding style issues

* Update vset instructions

Signed-off-by: BrighterW <xinlai.w@rioslab.org>
Signed-off-by: Xinlai Wan <xinlai.w@rioslab.org>
Co-authored-by: Nicolas Brunie <nibrunie@gmail.com>
Co-authored-by: Jessica Clarke <jrtc27@jrtc27.com>