[robotpy] Port more wpilibc tests to python (#8903)

I tasked Claude with converting the existing C++ tests to python for
wpilib. I gave it a decent review for comparison to the existing tests,
and it seems to have covered everything. I did do some small cleanup in
a couple of places. One notable test that is missing is the LED
patterns, but that is getting handled in
[mostrobotpy](https://github.com/robotpy/mostrobotpy/pull/254) land.

wpilibc/src/test/python/smartdashboard/test_mechanism2d.py

@@ -0,0 +1,89 @@
+import pytest
+
+from ntcore import NetworkTableInstance
+from wpilib import Mechanism2d, MechanismLigament2d, MechanismRoot2d, SmartDashboard
+from wpiutil import Color8Bit
+
+
+def test_create_mechanism():
+    m = Mechanism2d(100, 100)
+    r1 = m.getRoot("r1", 10, 10)
+    l1 = r1.appendLigament("l1", 4, 3)
+    l2 = l1.appendLigament("l2", 4, 3)
+    assert l2 is not None
+
+
+def test_canvas(nt: NetworkTableInstance):
+    mechanism = Mechanism2d(5, 10)
+    dims_entry = nt.getEntry("/SmartDashboard/mechanism/dims")
+    color_entry = nt.getEntry("/SmartDashboard/mechanism/backgroundColor")
+
+    SmartDashboard.putData("mechanism", mechanism)
+    SmartDashboard.updateValues()
+
+    dims = dims_entry.getDoubleArray([])
+    assert dims[0] == pytest.approx(5.0)
+    assert dims[1] == pytest.approx(10.0)
+    assert color_entry.getString("") == "#000020"
+
+    mechanism.setBackgroundColor(Color8Bit(255, 255, 255))
+    SmartDashboard.updateValues()
+    assert color_entry.getString("") == "#FFFFFF"
+
+
+def test_root(nt: NetworkTableInstance):
+    mechanism = Mechanism2d(5, 10)
+    x_entry = nt.getEntry("/SmartDashboard/mechanism/root/x")
+    y_entry = nt.getEntry("/SmartDashboard/mechanism/root/y")
+
+    root = mechanism.getRoot("root", 1, 2)
+    SmartDashboard.putData("mechanism", mechanism)
+    SmartDashboard.updateValues()
+
+    assert x_entry.getDouble(0.0) == pytest.approx(1.0)
+    assert y_entry.getDouble(0.0) == pytest.approx(2.0)
+
+    root.setPosition(2, 4)
+    SmartDashboard.updateValues()
+
+    assert x_entry.getDouble(0.0) == pytest.approx(2.0)
+    assert y_entry.getDouble(0.0) == pytest.approx(4.0)
+
+
+def test_ligament(nt: NetworkTableInstance):
+    mechanism = Mechanism2d(5, 10)
+    angle_entry = nt.getEntry("/SmartDashboard/mechanism/root/ligament/angle")
+    color_entry = nt.getEntry("/SmartDashboard/mechanism/root/ligament/color")
+    length_entry = nt.getEntry("/SmartDashboard/mechanism/root/ligament/length")
+    weight_entry = nt.getEntry("/SmartDashboard/mechanism/root/ligament/weight")
+
+    root = mechanism.getRoot("root", 1, 2)
+    ligament = root.appendLigament("ligament", 3, 90, 1, Color8Bit(255, 255, 255))
+    SmartDashboard.putData("mechanism", mechanism)
+
+    assert ligament.getAngle() == pytest.approx(angle_entry.getDouble(0.0))
+    assert ligament.getColor().hexString() == color_entry.getString("")
+    assert ligament.getLength() == pytest.approx(length_entry.getDouble(0.0))
+    assert ligament.getLineWeight() == pytest.approx(weight_entry.getDouble(0.0))
+
+    ligament.setAngle(45)
+    ligament.setColor(Color8Bit(0, 0, 0))
+    ligament.setLength(2)
+    ligament.setLineWeight(4)
+    SmartDashboard.updateValues()
+
+    assert ligament.getAngle() == pytest.approx(angle_entry.getDouble(0.0))
+    assert ligament.getColor().hexString() == color_entry.getString("")
+    assert ligament.getLength() == pytest.approx(length_entry.getDouble(0.0))
+    assert ligament.getLineWeight() == pytest.approx(weight_entry.getDouble(0.0))
+
+    angle_entry.setDouble(22.5)
+    color_entry.setString("#FF00FF")
+    length_entry.setDouble(4.0)
+    weight_entry.setDouble(6.0)
+    SmartDashboard.updateValues()
+
+    assert ligament.getAngle() == pytest.approx(angle_entry.getDouble(0.0))
+    assert ligament.getColor().hexString() == color_entry.getString("")
+    assert ligament.getLength() == pytest.approx(length_entry.getDouble(0.0))
+    assert ligament.getLineWeight() == pytest.approx(weight_entry.getDouble(0.0))