Add example input/output tuturials

[nwlambert]

Add first drafts of tutorial notebooks for HEOM input output feature.

These require qutip/qutip#2590 to function.

Todo list:

• Improve and expand explanation of both notebooks (the Markovian Waveguide one in particular needs more detail)
• Add third additional notebook showing non-Markovian waveguide example (maybe)

The waveguide example should be available soon also in the article https://arxiv.org/abs/2408.12221

Some of the functions used to define the waveguide correlations and parameters are taken from the code by mauro
https://github.com/mcirio/io-HEOM-Markovian/ and adapted under the MIT license for use here.