Changes the `Error::WithHint::hint` field to use a `String` type instead of
`&'static str`. This allows the caller to provide extra hint
information.
To make it easier to use an `Error::with_hint` constructor is added.
The `help` module is no longer needed, since `clap` handles that.
This meant that the re-exports of each command's `ABOUT` could be removed and
the `const`s can now be private.
This patch adds the `cob::common::Title` struct, this allows instead of
using `std::str::String` or generics and traits for it, to define more
precisely what a title should be.
It trims the provided string and makes sure it contains no carriage
return or new line characters.
Where a `std::str::String` makes more sense so it's easier to mutate it,
we keep the code as is.
Co-authored-by: Fintan Halpenny <fintan.halpenny@gmail.com>