Cleanup: fix typos in blender addons

add_mesh_extra_objects/Blocks.py

io_mesh_stl/blender_utils.py

io_mesh_stl/stl_utils.py

io_scene_fbx/export_fbx_bin.py

io_scene_gltf2/blender/com/gltf2_blender_ui.py

...r/exp/gltf2_blender_gather_animation_sampler_keyframes.py

...e_gltf2/blender/imp/gltf2_blender_pbrMetallicRoughness.py

materials_utils/functions.py

power_sequencer/operators/fade_add.py

power_sequencer/operators/mouse_trim_modal.py

precision_drawing_tools/pdt_tangent.py

render_povray/particles.py

rigify/rigs/limbs/limb_rigs.py