[wpimath] Add protobuf/struct for trivial types (#5935)

This implements de/serialization for the types that aren't templated (SwerveDriveKinematics) in C++ or where there is no trivial way to go round-trip (Splines) for the messages.

wpimath/src/test/native/cpp/trajectory/proto/TrajectoryProtoTest.cpp

@@ -0,0 +1,35 @@
+// Copyright (c) FIRST and other WPILib contributors.
+// Open Source Software; you can modify and/or share it under the terms of
+// the WPILib BSD license file in the root directory of this project.
+
+#include <gtest/gtest.h>
+
+#include "frc/trajectory/Trajectory.h"
+#include "trajectory.pb.h"
+
+using namespace frc;
+
+namespace {
+
+using ProtoType = wpi::Protobuf<frc::Trajectory>;
+
+const Trajectory kExpectedData = Trajectory{std::vector<frc::Trajectory::State>{
+    Trajectory::State{1.1_s, 2.2_mps, 3.3_mps_sq,
+                      Pose2d(Translation2d(1.1_m, 2.2_m), Rotation2d(2.2_rad)),
+                      units::curvature_t{6.6}},
+    Trajectory::State{2.1_s, 2.2_mps, 3.3_mps_sq,
+                      Pose2d(Translation2d(2.1_m, 2.2_m), Rotation2d(2.2_rad)),
+                      units::curvature_t{6.6}},
+    Trajectory::State{3.1_s, 2.2_mps, 3.3_mps_sq,
+                      Pose2d(Translation2d(3.1_m, 2.2_m), Rotation2d(2.2_rad)),
+                      units::curvature_t{6.6}}}};
+}  // namespace
+
+TEST(TrajectoryProtoTest, Roundtrip) {
+  google::protobuf::Arena arena;
+  google::protobuf::Message* proto = ProtoType::New(&arena);
+  ProtoType::Pack(proto, kExpectedData);
+
+  Trajectory unpacked_data = ProtoType::Unpack(*proto);
+  EXPECT_EQ(kExpectedData.States(), unpacked_data.States());
+}

wpimath/src/test/native/cpp/trajectory/proto/TrajectoryStateProtoTest.cpp

@@ -0,0 +1,34 @@
+// Copyright (c) FIRST and other WPILib contributors.
+// Open Source Software; you can modify and/or share it under the terms of
+// the WPILib BSD license file in the root directory of this project.
+
+#include <gtest/gtest.h>
+
+#include "frc/trajectory/Trajectory.h"
+#include "trajectory.pb.h"
+
+using namespace frc;
+
+namespace {
+
+using ProtoType = wpi::Protobuf<frc::Trajectory::State>;
+
+const Trajectory::State kExpectedData = Trajectory::State{
+    1.91_s, 4.4_mps, 17.4_mps_sq,
+    Pose2d{Translation2d{1.74_m, 19.1_m}, Rotation2d{22.9_rad}},
+    units::curvature_t{0.174}};
+}  // namespace
+
+TEST(TrajectoryStateProtoTest, Roundtrip) {
+  google::protobuf::Arena arena;
+  google::protobuf::Message* proto = ProtoType::New(&arena);
+  ProtoType::Pack(proto, kExpectedData);
+
+  Trajectory::State unpacked_data = ProtoType::Unpack(*proto);
+  EXPECT_EQ(kExpectedData.t.value(), unpacked_data.t.value());
+  EXPECT_EQ(kExpectedData.velocity.value(), unpacked_data.velocity.value());
+  EXPECT_EQ(kExpectedData.acceleration.value(),
+            unpacked_data.acceleration.value());
+  EXPECT_EQ(kExpectedData.pose, unpacked_data.pose);
+  EXPECT_EQ(kExpectedData.curvature.value(), unpacked_data.curvature.value());
+}