[ENHANCEMENT] Publish `LOAD_LIBRARY_TIME_OUT`as environment variables

[Noordsestern]

Is your enhancement request related to a problem? Please describe.
LOAD_LIBRARY_TIME_OUT is a constant used to limit the time a library requires to be instantiated. The limit is currently set to 10 seconds.

The purpose of that timeout is prevent bad library design, where constructors compute expensive operations. Constructors must not contain expensive operations as all kind of tools require to create an instance of a library, but don't execute it (i.e. libdoc or robotcode).

The issue comes with big libraries with many imports and python environments that are installed in slow environments (i.e. remote network folders). Due to the environment setup the library instantiation fails even before the constructor is executed, hence during loading module imports.

Describe the solution you'd like
Hence the TIMEOUT is depending on environment setup, make the TIMEOUT an environment variable. It's in responsibility of the user to consciously overwrite that property and live with the desired consequences.

Describe alternatives you've considered
Different environment setup cannot always be achieved, due to corporate restrictions.