Add thanks issue template, and improve the bug and feature request templates (Lombiq Technologies: OCORE-205)

[Piedone]

Fix #16894

[MikeAlhayek]

Are we seeing an increase in "Thank you" issues that we need to dedicate a template for it?

[Piedone]

We have no thank you issues since we don't allow thank you issues now. This is to inspire people to express them liking OC.

[MikeAlhayek]

I doubt this is useful at all. but feel free to merge it and see how many thank you we'll see. and why would we even need that? we'll just start managing thank you notes

[Piedone]

I elaborated the rationale under the issue and also yesterday at the meeting: it's about gathering positive feedback (which will help us keep contributing) and data about how people use OC.

But OK then. We'll see if people will submit such issues, and if it's useful, but there's really no cost to try it.