Outline / breadcrumb improvements

[notpeter]

In the following Dart code breadcrumbs are shown for each line as comment:

class Test {                    // file > class Test
    void main() {               // file > class Test, or file > class Test > main when on "void main() " part
                                // file > class Test, or file > class Test > test when on "void test() " part
        void test() {           // file > class Test
                                // file > class Test
        }                       // file > class Test
                                // file > class Test
        print('hi');
    }
}

The expected breadcrumbs would be file > class Test > main > test when the cursor is on void test() { ... }, and similarly file > class Test > main outside of that block but in void main() { ... } and so on.

A similarly structured Rust code shows breadcrumbs as expected.

Originally reported by @osa1 in:

• Bad breadcrumbs in Dart zed-industries/zed#15484

[notpeter]

I can reproduce this is still an issue with the dart extension.
It appears the outline.scm is quite minimal, basically additional tree-sitter queries need to be added to better support defining the AST structure. Open dev: show syntax tree view to see the live tree-sitter output. In this example I believe there needs to be an additional query added for local_function_declaration.

More docs on outline.scm can be found here:

• https://zed.dev/docs/extensions/languages#code-outlinestructure