Use Expecto's `runTestsInAssemblyWithCLIArgs` function to enable test discovery using `[<Tests>]` annotation

[tw0po1nt]

Is your feature request related to a problem? Please describe.
Currently, the dominant approach to providing tests to the test runner in this repository is manually via Expecto's list-based API. This is error-prone, as it is easy to omit tests (I did so in #314).

Describe the solution you'd like
Expecto has a function named runTestsInAssemblyWithCLIArgs that allows for test discovery via an annotation [<Tests>]. This was the approach used in FsToolkit.ErrorHandling.TaskResult.Tests prior to it being removed in #314. I think we should move toward this approach for the whole solution, if possible.

Describe alternatives you've considered
Not forgetting to add tests to the list

[TheAngryByrd]

The problem here is this doesn't work for Fable tests. Thus why it's kept to be List oriented, so you don't miss the Fable implementation. Unless the Fable test frameworks somehow implement reflection to also work with this, it's unlikely I'll want to change this.

[tw0po1nt]

That makes sense! It'd be nice to smooth the experience over for testing Fable vs .NET. Maybe an ask for Fable frameworks that could eventually trickle here to enable this.

[TheAngryByrd]

Fable support for reflection is extremely limited and would be a giant undertaking to make work.

[TheAngryByrd]

Gonna close this for now. We can re-open if any upstream things change.