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.

[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.