Wrapping Previously Installed Libraries by a Conda Package

## Discussion Topic: Package type between CDT and Conventional

How do I develop a package which wraps a library not installed by conda?
An example of such libraries would be those whose distribution is limited or restricted.
e.g.
- Oracle JDK
- mpich and openmpi: https://conda-forge.org/docs/user/tipsandtricks.html#using-external-message-passing-interface-mpi-libraries

Context:
We write open-source plugins for various proprietary software (mostly modeling tools (UML, SysML, etc.)).
While developing (testing) these tools we need to cycle through all the versions of those tools and their libraries.
The binaries for these libraries are not freely distributed; the access to these libraries is not a simple download from a url.
I can make conda-forge packages for these libraries but the `source: url:` is problematic.

Case Study:
An example is the oracle-jdk; the [PR for oracle-jdk package](https://github.com/conda-forge/staged-recipes/pull/4032).
It illustrates the point, the contributor eventually abandoned it.
There is [another oracle jdk package](https://anaconda.org/gtcg/oraclejdk) which seems to work on linux.

Goal:
Develop a consistent way of handling packages which wrap libraries which are not installed using conda.

Ref:

- https://docs.conda.io/projects/conda-build/en/latest/user-guide/environment-variables.html