Tree: update selection affordance in ancestors mode

[ashetland]

Check existing issues

• [X] I have checked for existing issues to avoid duplicates

Description

Update Tree selection-mode="ancestors" to use icons instead of checkboxes. This will visually align Tree with updates from epic #7181.

Acceptance Criteria

Selection icons and hover states updated to match Figma designs.

Relevant Info

@geospatialem @brittneytewks These designs were originally included on a related, but separate issue. Logging this new one for inclusion in epic #7181.

Which Component

Tree, Tree Item

Example Use Case

No response

Priority impact

p3 - want for upcoming milestone

Calcite package

• [X] @esri/calcite-components
• [ ] @esri/calcite-components-angular
• [ ] @esri/calcite-components-react
• [ ] @esri/calcite-design-tokens
• [ ] @esri/eslint-plugin-calcite-components

Esri team

Calcite (design)

[github-actions[bot]]

cc @geospatialem, @brittneytewks

[github-actions[bot]]

Installed and assigned for verification.

[geospatialem]

The above was included in PR https://github.com/Esri/calcite-design-system/pull/9849, where the following was added to the tree-item:

https://github.com/Esri/calcite-design-system/blob/f2aa976f3c0d0ce69aa184a835da628e9898a4bd/packages/calcite-components/src/components/tree-item/tree-item.tsx#L235-L245