Fix broken references to file upload variants

[dillonkearns]

When I ran the instructions in the repo and example folder (running lamdera live from examples/counter and going to http://localhost:8000/tests/EndToEndTests.elm), I got these errors:

-- NAMING ERROR  program-test/example/counter/tests/EndToEndTests.elm

I cannot find a `CancelFileUpload` variant:

35|     , handleFileUpload = always CancelFileUpload
                                    ^^^^^^^^^^^^^^^^
These names seem close though:

    UnhandledFileUpload
    UnhandledMultiFileUpload
    Dom.Viewport
    BadUrlResponse

Note: Evergreen migrations need access to all custom type variants. Make sure
both `CancelFileUpload` and `Evergreen.VX.CancelFileUpload` are exposed.

Hint: Read <https://elm-lang.org/0.19.1/imports> to see how `import`
declarations work in Elm.


-- NAMING ERROR  program-test/example/counter/tests/EndToEndTests.elm

I cannot find a `CancelMultipleFilesUpload` variant:

36|     , handleMultipleFilesUpload = always CancelMultipleFilesUpload
                                             ^^^^^^^^^^^^^^^^^^^^^^^^^
These names seem close though:

    UnhandledMultiFileUpload
    UploadMultipleFiles
    UnhandledFileUpload
    Effect.Test.UnhandledFileUpload

Note: Evergreen migrations need access to all custom type variants. Make sure
both `CancelMultipleFilesUpload` and `Evergreen.VX.CancelMultipleFilesUpload`
are exposed.

Hint: Read <https://elm-lang.org/0.19.1/imports> to see how `import`
declarations work in Elm.

Based on the types required here these seem to be the new variant names that are needed.

[MartinSStewart]

Thanks! I really should get around to adding CI that checks the examples so they don't get out of sync.