Make Map insertion functions total

[rkallos]

Thanks to #3201, it's now possible to make Map.insert & friends total functions. Not only that, but Map.insert should be slightly faster in the case where the insertion causes the underlying array to grow, as it is no longer necessary to do the lookup for the final value.

I suspect this would constitute a pretty large breaking change, as I'm sure code like try map.insert(k, v)? end is pretty common, and after this change it would be a compile-time error.

This PR is incomplete. There are some more partial-not-partial functions that can be fixed, like Map.insert_if_absent.

[SeanTAllen]

@rkallos you'll need to rebase against master to pick up the removal of pcre2 so that when you start up on this again, it can work with the latest CI images.

[rkallos]

Thanks @SeanTAllen for adding the label and letting me know to rebase. I think this is ready for review now.

[jemc]

It's a beautiful thing!

[rkallos]

Rebased and squashed :)

[SeanTAllen]

@rkallos can you add release notes for this change? including "what your code looks like before and after" so folks know how to update?

[rkallos]

Before this change, code that inserts into maps might look like:

try map.insert("key", 1)? end

try map.insert_if_absent("key", 5)? end

try
  map.upsert("key", 1, {(current, provided) => current + provided})?
end

After this change, the question marks and the surrounding try expressions can be removed. Respectively, the above blocks become:

map.insert("key", 1)

map.insert_if_absent("key", 5)

map.upsert("key", 1, {(current, provided) => current + provided})?