Add WSG50 with deformable bubble gripper

[xuchenhan-tri]

Twin Drake PR: RobotLocomotion/drake#21240

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This change is 

[xuchenhan-tri]

+@jwnimmer-tri for reviews please? I figured you might have opinions on how I split the models files across models/ and drake/

Sherm already reviewed the content of the sdf file.

Reviewable status: all discussions resolved, LGTM missing from assignee jwnimmer-tri, platform LGTM missing (waiting on @jwnimmer-tri)

[jwnimmer-tri]

For the files being added here, the file arrangement / choice of directories looks good to me. I don't have time to review further -- and generally same feature reviewer should do both twin PRs anyway.

In terms of which files go where between drake vs drake_models, the invariant we want is that meshes live in this repository, and any sdformat / urdf / mjcf files that cite those meshes live here as well (so that e.g. renaming a mesh file is not a cross-repo twin PR change).

[xuchenhan-tri]

In terms of which files go where between drake vs drake_models, the invariant we want is that meshes live in this repository, and any sdformat / urdf / mjcf files that cite those meshes live here as well

That makes sense and is mostly respected by my PRs. The only sticking point is that I left the teddy bear mesh in the drake repo. The size of the dir remains under 100kB though.

+@sherm1 for review.

Reviewable status: all discussions resolved, LGTM missing from assignee jwnimmer-tri, LGTM missing from assignee sherm1, platform LGTM missing (waiting on @jwnimmer-tri)

[sherm1]

-@jwnimmer-tri

Reviewed 5 of 5 files at r1, all commit messages.
Reviewable status: complete! all discussions resolved, platform LGTM from [sherm1] (waiting on @jwnimmer-tri)

[jwnimmer-tri]

In #62, I'm asking Sean to fix the filenames here. When there are lots of models in the same assets subdir, names like dots.png and dot_pattern.mtl are too difficult to pair with their parent. They should have been textured_bubble.mtl and textured_bubble.png.