Fix perspective crate, link perspective-server as static lib

[texodus]

#2707 split the perspective-server crate into a stand-alone .so for the C++ part of the code base that needed be be built, bundled and imported separately from the Rust client. This fixed perspective-python when compiled via Emscripten, but broke the perspectve Rust crate and caused general build havoc.

This PR partially reverts #2707:

• Deletes perspective-python's duplication of the cmake build logic, src tree cloning, etc.
• Modifies perspective-server to build the C++ deps as a static lib.
• Adds perspective-rs to the build and CI system. This library is now built, tested and packaged on CI.
• Re-implemented perspective-server internal C++ library binding, from cxx to a hand-rolled FFI.