Custom mouse and key actions through config

[ZacZhangzhuo]

This PR will alow Custom mouse and key actions through config. Users can define their keys in the config file.

What type of change is this?

• Add example example_custom_keys.py in the examples/control.
• Action class which controls all the key actions.

Checklist

Put an x in the boxes that apply. You can also fill these out after creating the PR. If you're unsure about any of them, don't hesitate to ask. We're here to help! This is simply a reminder of what we are going to look for before merging your code.

• [x] I added a line to the CHANGELOG.md file in the Unreleased section under the most fitting heading (e.g. Added, Changed, Removed).
• [x] I ran all tests on my computer and it's all green (i.e. invoke test).
• [x] I ran lint on my computer and there are no errors (i.e. invoke lint).
• [ ] I added new functions/classes and made them available on a second-level import, e.g. compas.datastructures.Mesh.
• [x] I have added tests that prove my fix is effective or that my feature works.
• [x] I have added necessary documentation (if appropriate)

[ZacZhangzhuo]

Would this be the last PR for compas_view2? @Licini

[Licini]

Would this be the last PR for compas_view2? @Licini

Yes 😎