add zed2 wrapper as a submodule

[nico-palmar]

Added the zed-ros2-wrapper as a submodule in our repo.

Also updated the readme to include recursive subclone (ie clone the submodule automatically).

Im not sure if I need to add any other dependencies/checks here or if I need to add any of the packages to ci.yaml (I assume I dont but just checking)

[keyonjerome]

Does this have to be a submodule rather than a normal package we clone along with the others, such as vectornav?

[nico-palmar]

Does this have to be a submodule rather than a normal package we clone along with the others, such as vectornav?

Nope, ticket said submodule so I assumed you meant actual submodule. Changed it to just an upstream dependency - not sure if I need to add anything else. Lmk @keyonjerome

[keyonjerome]

Thanks -- yeah the submodule part was just me not thinking. Definitely works better as an upstream dependency. Feel free to merge this into your branch and deal with the failing lint checks there.

[keyonjerome]

I'd like specifying a specific commit here instead of master such that our repo doesn't randomly break in the case that they change something on the stereolabs/zed-ros2-wrapper side.