Replace X button with dropdown menu in CollectionItemRow

[Nixxx19]

Issue:

Fixes #3883
Fixes #3881

The "X" button in the Collection sketch list view was confusing — it wasn't clear whether it removed the sketch from the collection or deleted it entirely. This PR replaces it with a dropdown menu consistent with the rest of the editor's UI (e.g., My Sketches, My Collections pages).

Demo:

After: A dropdown menu (▾) matching the style used on the My Sketches and My Collections pages, with a "Remove sketch from collection" option.

Changes:

• Replaced the RemoveIcon button and Tooltip with TableDropdown and MenuItem components in CollectionItemRow.jsx
• Added a SketchlistDropdownColumn styled component for consistent positioning with other table dropdowns
• Removed overflow: hidden from .collection-container and .collection-content to prevent the dropdown from being clipped
• Removed unused .collection-row__action-column and .collection-row__remove-button styles from _collection.scss
• Updated unit tests to reflect the new dropdown behavior

I have verified that this pull request:

• has no linting errors (npm run lint)
• has no test errors (npm run test)
• has no typecheck errors (npm run typecheck)
• is from a uniquely-named feature branch and is up to date with the develop branch.
• is descriptively named and links to an issue number, i.e. Fixes #123
• meets the standards outlined in the accessibility guidelines

[raclim]

Thanks so much for the quick turnaround on this! I think the changes here overall look awesome!

I think the only suggested changes I have here are UI-based:

• Would it be possible to update the text to "Remove from Collection" add title casing, i.e ("Remove From Collection"). Currently, I feel like the text is a bit lengthy, making the dropdown appear a little awkward visually. I'm not entirely sure if shortening the text could help alleviate it, but if it's still wrapping onto the second line, then maybe we could try adjusting the width or margins of the dropdown menu as well?

Please let me know if you have any other thoughts on this as well!