[wpimath] Remove unit suffixes from variable names (#7529)

* Move units into API docs instead because suffixes make user code verbose and hard to read
* Rename trackWidth to trackwidth
* Make ultrasonic classes use meters instead of a mix of m, cm, mm, ft,
  and inches

sysid/src/main/native/include/sysid/analysis/TrackwidthAnalysis.h

@@ -10,14 +10,14 @@
 namespace sysid {
 
 /**
- * Calculates the track width given the left distance, right distance, and
+ * Calculates the trackwidth given the left distance, right distance, and
  * accumulated gyro angle.
  *
  * @param l     The distance traveled by the left side of the drivetrain.
  * @param r     The distance traveled by the right side of the drivetrain.
  * @param accum The accumulated gyro angle.
  */
-constexpr double CalculateTrackWidth(double l, double r,
+constexpr double CalculateTrackwidth(double l, double r,
                                      units::radian_t accum) {
   // The below comes from solving ω = (vr − vl) / 2r for 2r.
   return (gcem::abs(r) + gcem::abs(l)) / gcem::abs(accum.value());

sysid/src/test/native/cpp/analysis/TrackwidthAnalysisTest.cpp

@@ -4,9 +4,9 @@
 
 #include <gtest/gtest.h>
 
-#include "sysid/analysis/TrackWidthAnalysis.h"
+#include "sysid/analysis/TrackwidthAnalysis.h"
 
-TEST(TrackWidthAnalysisTest, Calculate) {
-  double result = sysid::CalculateTrackWidth(-0.5386, 0.5386, 90_deg);
+TEST(TrackwidthAnalysisTest, Calculate) {
+  double result = sysid::CalculateTrackwidth(-0.5386, 0.5386, 90_deg);
   EXPECT_NEAR(result, 0.6858, 1E-4);
 }