[chore] Simplify email types

[elland]

This factors out one of our email types in favour of a validated email, this means a lot of tests that created arbitrary bytestrings became invalid and were replaced with simple valid emails, this might have caused redundancy in some of the golden tests.

https://wearezeta.atlassian.net/browse/WPB-665

Checklist

• Add a new entry in an appropriate subdirectory of changelog.d
• Read and follow the PR guidelines

[mdimjasevic]

There's a lot of diff in golden tests. They pretty much all seem to be facing the same issue: a change in the string value where no change was needed, at least that's my hunch (e.g., replacing Email {emailLocal = "OR\32966c", emailDomain = "\RS\ENQr"} with unsafeEmailAddress "some" "example". If it's the case that the former is not a valid email address, then I can see how the change is justified, but please confirm.

[mdimjasevic]

There's stuff to improve. See comments inlined.

[mdimjasevic]

Assuming you fix the two remaining TODOs, this is good to go.

In Spar.Scim.User you still have this comment:
TODO(elland): verify with fisx if this still applies.
And another one:
TODO: validate fallback emails?