Docs: add a more advanced custom function tutorial

[kirszenbaum]

Description

As discussed here, we should add a more advanced guide on implementng custom functions.

Links

https://handsontable.github.io/hyperformula/guide/custom-functions.html#implementing-your-custom-function
#968
#1090

Type of issue

• Missing documentation
• Error in the documentation
• Request for a demo
• Request for a tutorial, guide etc.
• Other issues, suggestions or ideas

[warpech]

The goal here is to show in the docs how to make a function that:

• accepts arguments (one of which might be a range, expression, etc)
• is comprehensive (is protected from edge cases, does not blow up by being too naive)
• is testable (there is an example of a unit test)

[sequba]

Consider creating an example of a custom array function. See: #843

[sequba]

It turns out our current guide contains bugs that cause problems when trying to implement a custom function with arguments:

• Incomplete documentation for custom function arguments validation #1090
• https://handsoncode.slack.com/archives/C031GBX62SE/p1668695428147239 (internal discussion)

After the research phase, we might be able to formulate answers to the above questions.

[sequba]

We've decided to make this guide as comprehensive as possible and request the review from external consulting company.

[sequba]

Released with HyperFormula 2.3.0.