Allow bode and bodeplot to use a range of frequencies and a freq to calculate the freq. vector

[VaiTon]

• Added docs
• Added tests

[baggepinnen]

Hello and thank you for your PR! A few general comments to start off with

• Please consider submitting PRs without running a formatter. on the whole file. The formatter makes lots of changes that are unrelated to the PR which makes it hard to see what you have actually changed in the PR, and I also generally do not like the changes the formatter does, hence it's not being used on this repo.
• Please consider opening an issue before submitting a PR so that we can discuss whether or not the idea is worthwhile pursuing. In this case, we already have a PR that attempts to do something similar, but it takes a much wider approach applying to all frequency-response functions rather than just Bode: WIP: Adaptive sampling #532