refactor: cleanup gravity constant handling (#35866)

* refactor: move lateral methods from init to lateral.py (#2594)

* Extracting lateral methods to lateral.py

* cleaning

* more cleaning

* more cleaning

* Making sure it remains where it should

* Leave rate_limit where it belongs

* Moving things to `car/controls/`

* Moving rate limit to get a taste of the changes

* clean

* copy verbatim

* clean up

* more

* now we can format

---------

Co-authored-by: Shane Smiskol <shane@smiskol.com>

* No need to change order of import

* refactor: consolidate ACCELERATION_DUE_TO_GRAVITY import path

* bump opendbc

* update refs

* don't import from opendbc

---------

Co-authored-by: Shane Smiskol <shane@smiskol.com>
Co-authored-by: Adeeb Shihadeh <adeebshihadeh@gmail.com>

common/constants.py

@@ -1,6 +1,7 @@
 import numpy as np
 
-class Conversions:
+# conversions
+class CV:
   # Speed
   MPH_TO_KPH = 1.609344
   KPH_TO_MPH = 1. / MPH_TO_KPH
@@ -17,3 +18,6 @@ class Conversions:
 
   # Mass
   LB_TO_KG = 0.453592
+
+
+ACCELERATION_DUE_TO_GRAVITY = 9.81  # m/s^2