Expand the standard library

[pbiggar]

The standard library has a batteries-included approach for the standard modules: List, String, Int, Float, Result, Option, UUID, Date, Dict, Bool, Bytes, DB, HTTPClient and HTTP (response) modules.

We generally copy the Elm standard library where it makes sense: https://package.elm-lang.org/packages/elm/core/1.0.5/. We no longer add functions that would make more sense in the package manager (such as calls to HTTP/REST/JSON APIs). We do add Crypto functions as they are very hard to do in userspace and have performance needs.

Contributions of just one function is very welcome, and is a great early bugs for contributors.

We have an internal document on how to write standard library functions, which I'll add to this ticket later.

This explains how to write docstrings: https://github.com/darklang/dark/blob/master/docs/writing-docstrings.md.

Requests for new functions should each be a separate issue.

https://github.com/darklang/dark/labels/stdlib

[pbiggar]

Users have asked for:

• url decoding function
• date functions
• url builder
• Date formatting
• a bulk-add DB function

(TODO: make separate issues for these)

[tchak]

• List:shuffle
• figure out an ergonomic way to remove items from list - List::remove maybe?

[pingiun]

I did Crypto::md5 in #2483

And List::takeWhile in #2487

[mwz]

Date::atStartOfDay implemented in #2546.

[StachuDotNet]

merged this into #5239