Move to SimVascular

[mrp089]

This software originated from different "slicing tools" developed by @mrp089, @ktbolt, @lucapegolotti (and others?). As far as I know, this version is the fastest one, and I think a couple of people use it in the lab. Thus, I think it makes sense to move it to https://github.com/SimVascular

I'll add our usual GitHub Actions (code check, build, test) and a test case where we slice a vtu and compare it to a stored vtp. In the future, this could also be included in SimVascular as a post-processing option.

@ktbolt, is there anything else that should be added?

[ktbolt]

Go ahead and move it to https://github.com/SimVascular/Tools.

You should find a better name for the program, svSlice describes how it is implemented but not what it is actually used for.