Runtime tests using examples from docstrings

[aspeddro]

This PR is a proposal to add unit tests using docstrings. Currently the examples from docstrings have tests for compilation only.

• bsc emits the Js and passes the code to node using the --eval|-e argument.

TODO:

• Fix examples
• Remove examples with infinite loop, setIntervalFloat
• Update CHANGELOG

Changes

• Added assert_eq function
• Runtime errors captured
• Removed some examples with infinite loop at src/Core__Global.resi
• Removed Array from the test suite and moved it to docstrings.

DocTest script

• Added argument --ignore-runtime-tests
  • --ignore-runtime-tests 'RescriptCore.Array.toReversed,RescriptCore.Promise.withResolvers'. Array.toReversed and Promise.withResolvers are not supported by Node

[aspeddro]

Ready for review

[fhammerschmidt]

really nice work, some of the examples could be a bit more beginner-friendly but I know that is very hard to do without making them untestable.

[aspeddro]

I made a small improvement in two examples in the Null and Nullable module

[fhammerschmidt]

@zth what do you think?