Reduce overused pointers and dereferences

[trietsch]

While adding new features to the CLI, I've noticed that we overuse pointers. We don't need this many pointers. When should we use pointers?

1. While mutating an element passed as a parameter to a function
2. When you need to differentiate between nil and empty/default
3. When handling large structs, it might be useful

I propose to simplify the source code, by removing pointers where possible.

Information references:

• https://medium.com/@meeusdylan/when-to-use-pointers-in-go-44c15fe04eac
• https://qvault.io/golang/the-proper-use-of-pointers-in-go-golang/
• https://dhdersch.github.io/golang/2016/01/23/golang-when-to-use-string-pointers.html
• https://groups.google.com/g/golang-nuts/c/ZRKSJ3GPkLw

[trietsch]

@trietsch @bvdeenen @jankeesvanandel agreed on reducing the use of pointers.