IMU Preintegration

Add a symforce.slam.imu_preintegration module that provides a symbolic
implementation of tangent preintegration, and generates Python and C++
runtime functions for the main update function. Also adds a lightweight
Python wrapper class to maintain state and tests against GTSAM.

GitOrigin-RevId: 320a1690e2bef50bff14001408552976bfe2ee5c

Author: hayk-skydio

dev_requirements.txt

@@ -75,6 +75,8 @@ fonttools==4.33.3
     # via matplotlib
 graphviz==0.20
     # via symforce (setup.py)
+gtsam==4.1.1 ; python_version < "3.10"
+    # via symforce (setup.py)
 idna==3.3
     # via requests
 imagesize==1.3.0
@@ -181,6 +183,7 @@ numba==0.56.0
     # via symforce (setup.py)
 numpy==1.22.4
     # via
+    #   gtsam
     #   matplotlib
     #   numba
     #   pandas
@@ -239,6 +242,7 @@ pylint==2.14.0
     # via symforce (setup.py)
 pyparsing==3.0.9
     # via
+    #   gtsam
     #   matplotlib
     #   packaging
 pyrsistent==0.18.1