Add hamiltonian simulation function template

[garrison]

Summary

This adds the hamiltonian simulation template and creates a directory for other templates.

Companion to Qiskit/documentation#2276

Details and comments

I included some test infrastructure, too. There is one FIXME in that file that I do not have time to fix now.

Remaining action items

• Either: add hw results; or, get rid of cells that load hw result.
• Need to add the script output of the notebook, too. Usually this would not be included in version control since it is generated, but it is useful for a user to see.
• Write a bit more text in the READMEs