Consistent use of code style in `mice`

[hanneoberman]

• write style guide?
• apply style throughout mice (e.g. base vs tidy pipe)

[stefvanbuuren]

I am now on Positron and enabled the Air R language support module. What I found

• Air offers opinionated formatting with relatively few possibilities to deviate.
• I also have enabled the reformat on save, so that a lot of work is done subconsciously.
• Until now (only few days) it has worked flawlessly.
• I have enabled it for all my projects, so expect to see its effects in mice

[stefvanbuuren]

Commit 4bc509b is a first step in to tighter formatting using the Air formatter on all .R files.