[photonlib] Simulation robustness (#874)

- `PNPResults` can now be empty (`isPresent` = false)
- solvePNP methods actually handle errors and return empty `PNPResults`
  - This reveals an odd error where some inputs to `solvePNP_SQUARE()` resulted in an estimated transform with NaN values, and attempts to handle it
- Overwrites java changes from #817 since #742 had duplicate fixes
- Minor bugfixes

photon-lib/src/main/java/org/photonvision/estimation/PNPResults.java

@@ -36,7 +36,19 @@ import edu.wpi.first.math.geometry.Transform3d;
  * method.
  */
 public class PNPResults {
+    /**
+     * If this result is valid. A false value indicates there was an error in estimation, and this
+     * result should not be used.
+     */
+    public final boolean isPresent;
+
+    /**
+     * The best-fit transform. The coordinate frame of this transform depends on the method which gave
+     * this result.
+     */
     public final Transform3d best;
+
+    /** Reprojection error of the best solution, in pixels */
     public final double bestReprojErr;
 
     /**
@@ -51,8 +63,14 @@ public class PNPResults {
     /** If no alternate solution is found, this is 0 */
     public final double ambiguity;
 
+    /** An empty (invalid) result. */
     public PNPResults() {
-        this(new Transform3d(), new Transform3d(), 0, 0, 0);
+        this.isPresent = false;
+        this.best = new Transform3d();
+        this.alt = new Transform3d();
+        this.ambiguity = 0;
+        this.bestReprojErr = 0;
+        this.altReprojErr = 0;
     }
 
     public PNPResults(Transform3d best, double bestReprojErr) {
@@ -65,6 +83,7 @@ public class PNPResults {
             double ambiguity,
             double bestReprojErr,
             double altReprojErr) {
+        this.isPresent = true;
         this.best = best;
         this.alt = alt;
         this.ambiguity = ambiguity;