Add support for string interpolation to URI

[dimitribouniol]

Enables call sites that use URIs to allow for string literals that make use of interpolation (#2442).

app.get("hello") { req -> EventLoopFuture<String> in
    return req.client.get("\(Constants.basePath)/status")
    .flatMapThrowing { res throws in
        return "Hello, world!"
    }
}

[MrLotU]

I don't see a problem with this. CC @tanner0101, was there a specific reason not to do this? :)

[MrLotU]

I don't see a problem with this. CC @tanner0101, was there a specific reason not to do this? :)

[tanner0101]

LGTM, thanks @dimitribouniol. Two things:

• Would you mind adding a test? Just to make sure we don't accidentally lose this conformance if a refactor happens.
• Please format PR title / body as release notes: https://github.com/vapor/vapor/blob/master/.github/contributing.md#releases

[dimitribouniol]

@tanner0101 I've added to an existing test for URI parsing (for string interpolation too), and reformatted the PR's title and body. Please let me know if it needs any more changes! (I'll do the same to vapor/routing-kit#101 since it's pretty much the same PR, but for PathComponent)

[tanner0101]

Perfect, thanks!

[tanner0101]

These changes are now available in 4.23.0

[dimitribouniol]

@tanner0101 Thank you!