Prevent incorrect application of list widget on incompatible expressions

[Frizi]

Fixes #6760
Fixes #6747

Pull Request Description

Refactored the logic behind selecting appropriate widgets for span tree nodes. Now the bulk of it is moved into widget methods. When a given widget type is reporting to be not compatible with the expression, it will not be used even if the configuration was overriden using an method argument annotation. In that case, the usual logic for automatically selecting the appropriate widget will kick in.

Important Notes

Checklist

Please ensure that the following checklist has been satisfied before submitting the PR:

• The documentation has been updated, if necessary.
• Screenshots/screencasts have been attached, if there are any visual changes. For interactive or animated visual changes, a screencast is preferred.
• All code follows the
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  and
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  style guides. In case you are using a language not listed above, follow the Rust style guide.
• All code has been tested:
  • Unit tests have been written where possible.
  • If GUI codebase was changed, the GUI was tested when built using ./run ide build.

[farmaazon]

QA Report 🔴

1. One of the reported issues IDE doesn't render Vector concatenation. #6747 is not fully fixed: the second problem (expression not visible entirely on syntax error) still occurs:

(The node's expression is [1, 2, 3] + var1 + [4, 6, "])

2. I cannot connect to gray port if it's just a label (drop-downs and list editors can be connected into).

Similarly, here I cannot connect to "than", because the entire argument is selected:

[wdanilo]

@farmaazon good catches!

[Frizi]

@farmaazon Fixed mentioned issues, ready for second QA round.

Note that in above node with incorrect syntax, the right hand side "almost-vector" is not actually recognized as such due to how the expression is parsed. It is in fact not a even distinct subtree that could receive a single widget. Therefore it will not allow drag and drop.

Simplified span-tree:

[1, 2, 3] + var1 + [4, 6, "] Root
[1, 2, 3] + var1 + [4, 6, "]  ╰─Argument
[1, 2, 3] + var1 + [4, 6         ├─Argument
[1, 2, 3] + var1 + [4, 6         │  ╰─Argument
[1, 2, 3] + var1 + [4            │     ├─Argument
[1, 2, 3] + var1                 │     │  ├─Chained
[1, 2, 3]                        │     │  │  ├─Argument
[                                │     │  │  │  ├─Token
 1                               │     │  │  │  ├─Argument
  ,                              │     │  │  │  ├─Token
    2                            │     │  │  │  ├─Argument
     ,                           │     │  │  │  ├─Token
       3                         │     │  │  │  ├─Argument
        ]                        │     │  │  │  ╰─Token
          +                      │     │  │  ├─Operation
            var1                 │     │  │  ╰─Argument
                 +               │     │  ├─Operation
                   [4            │     │  ╰─Argument
                   [             │     │     ├─Operation       // This subtree looks weird, but all of those
                   [             │     │     │  ╰─Argument     // nodes received a distinct unique AST IDs.
                   [             │     │     │     ╰─Argument 
                   [             │     │     │        ╰─Token
                    4            │     │     ╰─Argument
                     ,           │     ├─Operation
                       6         │     ╰─Argument
                        ,        ├─Operation
                          "]     ╰─Argument

[farmaazon]

QA report 2: 🟢

Issues fixed, no more found.