Code Input Widget

[farmaazon]

Ctrl/Cmd click on parameter (defined by WidgetArgument presence) should turn it to "Code Input" widget, where user may put any arbitrary Enso code.

After accepting, the widget should stay, i.e. it should not be "broken" into other widgets - for example, when user type 2 + 2 and accepts it, the widget displaying 2 + 2 should stay instead of being turned into two numeric widgets with + between them.

The code-repair algorithm should be improved to handle some "breaking" code correctly:

• The unclosed text literals should be closed - TextLiteral printer could do that.
• Similarly, the unclosed ( should be automatically closed, because we cannot handle it by wrapping in ()
• Unclosed [ should be handled with current tree-repair approach, because it should be limited by encircling ().
• We should be sure we never interpret "empty node" as a block.

Otherwise, some code written in code input widget could break other widgets or the entire application

[farmaazon]

Refinement notes:

• Initially single line
• No highlighting
• We should ensure the connections are still working properly.
• What about breaking syntax? It should be handled in general: if AST node change would break parent after reparse, we should add (), and if still facing same issue, the edit should be discarded (being implemented by @kazcw)

[farmaazon]

Probably we should settle on "how to store metadata in our codebase - maybe in AST nodes?"

[farmaazon]

The metadata changes are tracked in:

• Keeping metadata as part of AST. #8804

This task should be done after them.

[farmaazon]

Added a section about proper AST repairing, to avoid issues discovered when numeric input widget accepted just any code.