Dropdown: selection icon updates

[ashetland]

Check existing issues

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

Description

To provide a clearer unselected multi-select state as well as align with updates to other Calcite components, update Dropdown's selection icons as documented in this Figma file.

This work was completed as part of epic #7181.

Screenshot for posterity:

Acceptance Criteria

Selection icons and hover states updated to match Figma designs.

Relevant Info

Calcite Icons v3.24.2 required.

Which Component

Dropdown

Example Use Case

No response

Priority impact

p3 - want for upcoming milestone

Calcite package

• [X] @esri/calcite-components
• [ ] @esri/calcite-components-react

Esri team

Calcite (design)

[github-actions[bot]]

cc @geospatialem, @brittneytewks

[brittneytewks]

Removed Figma changes label as this will be tracked in monday.com