Type annotation and type signatures support

[wdanilo]

This task is automatically imported from the old Task Issue Board and it was originally created by Wojciech Daniło.
Original issue is here.

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Implementation and tests of type annotations and type signatures, as described in the design doc.

In particular, the following code should parse:

main =
    val1 : Bool
    val2 : Text
    val3 : List Int
    val1 = True
    val2 = "hello" : Text
    val3 = foo ([1, 2] : Vector Int)

Comments:

Keziah Wesley reports a new STANDUP for today (2022-08-17):

Progress: Finished PR for UUIDs and comments. Also implemented type annotations / signatures. It should be finished by 2022-08-17.

Next Day: Next day I will be working on the ##182807114 task. Start on dual-Unicode-encodings. (Enso Bot - Aug 17, 2022)

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The [PR-3653](https://github.com//pull/3653) hasn't been integrated yet. It awaits approval from: @michael_mauderer , @farmaazon @murbanczyk and/or @wdanilo. Guys, can we get the PR reviewed so work on the [engine parser integration](https://www.pivotaltracker.com/n/projects/2539304/stories/182743471) can proceed? (jaroslavtulach - Aug 20, 2022)

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