fix: move from serialport/node-serialport

[reconbot]

Move the mock binding code from the monorepo - where it is now unfortunately has it part of a circular dependency with bindings-cpp and binding-interface. To update the interface, you need to publish the interface, update the monorepo's binding-mock but not any other package, publish that (difficult or impossible because of how lerna works), update bindings-cpp and then update the rest of the packages in the monorepo.

With this move to a new repository;

• update bindings-interface
• update bindings-mock
• update bindings-cpp
• update the serialport monorepo

This is still way to many steps but at least it's possible.

You might be asking why we have a bindings-interface package at all? Because every binding that the monorepo supports needs to impliment the same bindings interface.

Why does bindings-cpp use bindings-mock? This is to ensure we have the same test suite passing for both bindings. It's not ideal but I'm not sure how we might separate it out. It's a holdover from when they were in the same monorepo.

[reconbot]

This might be the case were just copying the same test suite to each package would help.