Import matplotlib 3D tools in the bodies of grasp plotting functions

[sea-bass]

Found an issue in which the ROS versions of matplotlib (installed via rosdep/apt) can conflict with pip installed versions -- specifically for the mpl_toolkits.mplot3d.axes3d module.

/usr/local/lib/python3.12/dist-packages/matplotlib/projections/__init__.py:63: 
UserWarning: Unable to import Axes3D. 
This may be due to multiple versions of Matplotlib being installed (e.g. as a system package and as a pip package).
As a result, the 3D projection is not available.

...

  File "/delib_ws/build/pyrobosim/pyrobosim/manipulation/grasping.py", line 9, in <module>
    from mpl_toolkits.mplot3d import Axes3D
  File "/usr/lib/python3/dist-packages/mpl_toolkits/mplot3d/__init__.py", line 1, in <module>
    from .axes3d import Axes3D
  File "/usr/lib/python3/dist-packages/mpl_toolkits/mplot3d/axes3d.py", line 35, in <module>
    from matplotlib.tri.triangulation import Triangulation
ModuleNotFoundError: No module named 'matplotlib.tri.triangulation'

So to be a bit safer, I'm moving these imports inside the 2 functions that actually use them.

[github-actions[bot]]

Coverage Report

File	Stmts	Miss	Cover	Missing
__init__.py	0	0	100%
core
__init__.py	9	0	100%
dynamics.py	47	1	97%	140
gazebo.py	136	8	94%	55, 124, 230, 244–248
hallway.py	94	8	91%	200, 242–245, 269–271
locations.py	131	18	86%	69, 71, 88, 104, 117–118, 120–121, 138, 196, 211, 236, 246, 302–303, 305–306, 335
objects.py	69	4	94%	78, 106, 137, 197
robot.py	464	69	85%	263–264, 276, 279, 283–284, 289–290, 336, 359–360, 401–403, 407–411, 436, 439, 443–445, 472, 474, 516–517, 519–520, 537–539, 555–557, 624–626, 651–653, 704–706, 775–777, 829–831, 854, 860, 863, 865, 867, 870–872, 882, 890, 896, 902, 908, 920, 962, 980, 983, 988
room.py	48	1	97%	113
world.py	805	189	76%	154–155, 191–192, 196, 270–271, 273–274, 304–305, 367, 381–382, 384–385, 400–402, 422–426, 428–430, 432–433, 436, 438–441, 445–449, 452–454, 457–468, 484–485, 503–505, 519, 521, 524–525, 530–532, 571, 573, 576–577, 582–584, 594–596, 631, 633, 636–637, 642–644, 667, 669, 672–673, 678–680, 726–727, 730, 751, 781–782, 793, 796, 804, 820–824, 826–828, 831–832, 835–838, 840, 843, 845–847, 849–851, 853, 868, 875, 886–890, 925–926, 930–931, 949–950, 956–957, 959–960, 962, 964–965, 967, 969–970, 980–981, 984, 986, 1000, 1002, 1009, 1056, 1087–1088, 1111–1112, 1116–1117, 1136–1137, 1141–1142, 1165, 1167–1168, 1204, 1221–1222, 1246, 1311, 1318, 1336–1339, 1351–1354, 1368, 1382, 1426–1427, 1479, 1559–1560, 1626, 1636
yaml_utils.py	109	6	94%	62, 66, 168–169, 188–189
gui
__init__.py	2	0	100%
main.py	263	71	73%	22–24, 45, 85, 89–92, 238–247, 259–268, 275–278, 280, 283–289, 293, 298–299, 303–304, 315, 355–356, 365–366, 370–371, 382, 385–388, 390–391, 394–397, 399–401, 405–408
world_canvas.py	302	58	80%	46–47, 49–53, 56, 169–172, 176–177, 182–183, 190, 192, 194, 251–253, 259, 261, 281–283, 328, 385–386, 413–414, 416, 418–420, 423–426, 428, 432–438, 441, 444–445, 461, 480, 523, 547, 577, 597, 614
manipulation
__init__.py	1	0	100%
grasping.py	237	64	73%	100, 108, 110–112, 114–122, 124, 132, 462, 464–466, 470–472, 566–567, 569–571, 574–578, 586, 589–591, 596–597, 603–607, 610–617, 620–622, 631, 633, 635–641
navigation
__init__.py	11	1	90%	37
a_star.py	77	11	85%	83–88, 90–92, 180, 189
execution.py	90	7	92%	73–75, 80–82, 119
occupancy_grid.py	139	14	89%	44–47, 49–53, 56, 192, 226, 234, 238
prm.py	56	4	92%	60–61, 140, 149
rrt.py	161	0	100%
visualization.py	32	6	81%	88–93
world_graph.py	58	4	93%	117, 120, 130, 139
planning
__init__.py	0	0	100%
actions.py	112	0	100%
planning/pddlstream
__init__.py	7	1	85%	13
defaultmappings.py	9	0	100%
planner.py	40	8	80%	119–126
primitives.py	61	4	93%	68, 82, 94, 232
utils.py	99	8	91%	66, 93, 105, 115–116, 207–208, 211
utils
__init_\.py	0	0	100%
general.py	33	4	87%	23, 45, 51–52
knowledge.py	154	22	85%	86, 117, 156–161, 163–164, 167–168, 170–173, 189, 204, 208, 250, 266, 329
motion.py	70	3	95%	93–94, 96
polygon.py	111	0	100%
pose.py	89	0	100%
search_graph.py	93	3	96%	240–242
trajectory.py	67	2	97%	130, 165
TOTAL	4286	599	86%

Tests	Skipped	Failures	Errors	Time
195	0 :zzz:	0 :x:	0 :fire:	3m 29s :stopwatch: