[wpiunits] Java units API rewrite (#6958)

Java generics are too limited to do what we need. This refactors generic code previously in Unit and Measure into unit-specific classes that can have unit-safe math operations (notably, times and divide) that can return values in known units instead of a wildcarded Measure<?>.

Unit-specific measure implementations are automatically generated by ./wpiunits/generate_units.py, which generates generic interfaces and mutable and immutable implementations of those interfaces. These make up the bulk of the diff of this PR (approximately 9300 LOC).

This also adds units for angular and linear velocities, accelerations, and momenta; moment of inertia; and torque.

wpiunits/src/test/java/edu/wpi/first/units/ExampleUnit.java

@@ -4,7 +4,9 @@
 
 package edu.wpi.first.units;
 
-class ExampleUnit extends Unit<ExampleUnit> {
+import edu.wpi.first.units.mutable.GenericMutableMeasureImpl;
+
+class ExampleUnit extends Unit {
   ExampleUnit(double baseUnitEquivalent) {
     this(baseUnitEquivalent, "Example", "ex");
   }
@@ -21,4 +23,28 @@ class ExampleUnit extends Unit<ExampleUnit> {
   ExampleUnit(double baseUnitEquivalent, String name, String symbol) {
     super(null, baseUnitEquivalent, name, symbol);
   }
+
+  public double convertFrom(double magnitude, ExampleUnit otherUnit) {
+    return fromBaseUnits(otherUnit.toBaseUnits(magnitude));
+  }
+
+  @Override
+  public Measure<ExampleUnit> of(double magnitude) {
+    return ImmutableMeasure.ofRelativeUnits(magnitude, this);
+  }
+
+  @Override
+  public Measure<ExampleUnit> ofBaseUnits(double baseUnitMagnitude) {
+    return ImmutableMeasure.ofBaseUnits(baseUnitMagnitude, this);
+  }
+
+  @Override
+  public MutableMeasure<ExampleUnit, ?, ?> mutable(double initialMagnitude) {
+    return new GenericMutableMeasureImpl<>(initialMagnitude, toBaseUnits(initialMagnitude), this);
+  }
+
+  @Override
+  public VelocityUnit<ExampleUnit> per(TimeUnit time) {
+    return VelocityUnit.combine(this, time);
+  }
 }