Network.Wai.Test: Add support for source locations to assertion primitives

[sol]

In addition, this will result in more readable test failures.

Before:

After:

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Before submitting your PR, check that you've:

• Bumped the version number
• Documented new APIs with Haddock markup
• Added @since declarations to the Haddock

After submitting your PR:

• Update the Changelog.md file with a link to your PR
• Check that CI passes (or if it fails, for reasons unrelated to your change, like CI timeouts)

[snoyberg]

Nice improvement, thanks!

[sol]

Thanks @snoyberg 👍

[snoyberg]

The WaiTestFailure change broke some other packages, I'm going to undo that and rerelease.

[sol]

@snoyberg bummer! It should have been a major version bump! My mistake, sorry for that!

I think dcd4e9f will not give us source locations. So reverting 357ef40 altogether would still be better than keeping parts of it.

Any chance that we can do this change with a major version bump?

[snoyberg]

I'm not interested in a major version bump for this. It should be possible to get source locations without one.

See also #813