CXXCBC-639: Allow to build both static and shared libraries

[avsej]

To avoid issues with generation of cmake helper scripts the following changes has been made:

• interface libraries that are used to carry compiler options and flags are declared as IMPORTED to avoid unnecessary INTERFACE_LINK dependencies for the static library

• jsonsl, asio and couchbase_backtrace libraries are not linked as a targets, but rather as a object files directly. This is also done to avoid announcing them as a transitive dependencies. All these libraries are hidden and never exposed.

• for other third-party dependencies do not disable install tasks, which generate export files

This patch also removes some unused cmake files (of crypto, sasl and operations/management directories).

Fixes #701