Clarify wording for some subtyping errors

[jasoncarr0]

A few subtyping errors were technically incorrect, or unnecessarily obtuse. This improves the wording to better clarify the meaning of these.

Fixes #3929 and #3928

[jasoncarr0]

Fixes #3929

This also applies a light bandage to #3928, while we very much should indicate which variables to consume and test that we can consume, updating the message helps indicate that consuming is even an option one should try.

[SeanTAllen]

Windows failure can be ignored. It's a CI error that is known and being looked into.

[SeanTAllen]

@jasoncarr0 is this ready other than the request for some release notes?

[ponylang-main]

Hi @jasoncarr0,

The changelog - fixed label was added to this pull request; all PRs with a changelog label need to have release notes included as part of the PR. If you haven't added release notes already, please do.

Release notes are added by creating a uniquely named file in the .release-notes directory. We suggest you call the file 3933.md to match the number of this pull request.

The basic format of the release notes (using markdown) should be:

## Title

End user description of changes, why it's important,
problems it solves etc.

If a breaking change, make sure to include 1 or more
examples what code would look like prior to this change
and how to update it to work after this change.

Thanks.

[SeanTAllen]

This addresses my intent with #3928, @jasoncarr0 during sync noted why he didn't think this was a fix. He had an idea for a deeper change where it would point out the variable that needs to be consumed. We discussed and he will be opening an issue for that.

Note to self: when squashing this to merge, make sure Fixes #3929 and #3928 is part of the comment.

[jasoncarr0]

@SeanTAllen Is this good to merge? Or is there anything else I missed

[SeanTAllen]

@jasoncarr0 it's fine. in the future you can do one line per paragraph in the release notes.