Include humanize_list function as a utility

[lengau]

What needs to get done

1. Copy this function and its relevant tests to craft-cli: https://github.com/canonical/craft-parts/blob/main/craft_parts/utils/formatting_utils.py
2. Make a craft-cli release
3. Update craft apps to reference this function instead of their own instances of it.
4. Make comments both here and in the craft-parts implementation that the function exists in the other location so we can copy bug fixes if needed. (No functional changes in craft-parts)

Why it needs to get done

Reduced copy/pasting of code for improved maintainability

[tigarmo]

Are we sure that this lib is the right place for this function? I can see that in the majority of cases the list if being humanized to be emitted/logged, but a side-effect of this is that the libs (like craft-parts and -providers) would start having craft-cli as a dependency. Which isn't awful necessarily , but is a consequence we need to consider.

...

At the same time, I'm not a huge fan of a grab-bag "craft-util" lib because it feels a bit chaotic, so I don't have any better suggestions, heh.

[tigarmo]

Maybe we could get this landed and use python-humanize?

[lengau]

@tigarmo I was just typing the same thing

[mr-cal]

python-humanize/humanize#110 landed this month in 4.11.0 so it is finally ready for us to use!