Build standalone camera packages

This basically reverse Lima.Core and camera dependency.

Processlib and Lima.Core should provide a devel package and install the headers, sip, and cmake files required to build cameras.

A CMakePackageConfigHelpers macros are used so that camera packages could do find_package(Lima). See Config packages for more info.

Dependency management between project (including Processlib) would be out of the scope of the build system, just like with any other third-party packages, which means someone would have to build and install (or just conda install) Processlib and Lima.Core in this order to start developing/debugging a camera.

A camera plugin template is available on Gitlab