Complete migration to swift-dependencies

[finestructure]

We've begun the transition to the @Dependency mechanism with PR #3399 where we converted the single function dependency

    var date: @Sendable () -> Date

to use the built in

        @Dependency(\.date.now) var now

mechanism.

A follow up PR #3438 does the some for a group of dependencies that are part of what's typically modelled in a "client" via the @DependencyClient macro.

These are basically the two types of dependencies we need to replace.

Once we have completed this transition, i.e. eliminated all of AppEnvironment, we have the opportunity to run tests that use dependencies in parallel.