Masterbar: display a pointer cursor for the sidebar menu toggle button

[ciampo]

Follow-up to #98510

Proposed Changes

• Change cursor to pointer for the sidebar menu trigger button in the masterbar

Why are these changes being made?

• For consistency with how pointers are displayed for other buttons across the site

Testing Instructions

• Load any page displaying the masterbar (eg. the home dashboard of any site)
• Resize the viewport to a width below 780px
• On a device with a pointer (ie. not a touch screen device), hover over the sidebar menu trigger button
• Make sure the pointer cursor is shown

Pre-merge Checklist

• Has the general commit checklist been followed? (PCYsg-hS-p2)
• Have you written new tests for your changes?
• Have you tested the feature in Simple (P9HQHe-k8-p2), Atomic (P9HQHe-jW-p2), and self-hosted Jetpack sites (PCYsg-g6b-p2)?
• Have you checked for TypeScript, React or other console errors?
• Have you used memoizing on expensive computations? More info in Memoizing with create-selector and Using memoizing selectors and Our Approach to Data
• Have we added the "[Status] String Freeze" label as soon as any new strings were ready for translation (p4TIVU-5Jq-p2)?
  • For UI changes, have we tested the change in various languages (for example, ES, PT, FR, or DE)? The length of text and words vary significantly between languages.
• For changes affecting Jetpack: Have we added the "[Status] Needs Privacy Updates" label if this pull request changes what data or activity we track or use (p4TIVU-aUh-p2)?

[github-actions]

Calypso Live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-130495

Jetpack Cloud live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-130495&env=jetpack

Automattic for Agencies live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-130495&env=a8c-for-agencies

[matticbot]

This PR modifies the release build for the following Calypso Apps:

For info about this notification, see here: PCYsg-OT6-p2

• notifications
• wpcom-block-editor

To test WordPress.com changes, run install-plugin.sh $pluginSlug fix/masterbar-sidebar-menu-trigger-cursor-pointer on your sandbox.

[matticbot]

This PR does not affect the size of JS and CSS bundles shipped to the user's browser.

Generated by performance advisor bot at iscalypsofastyet.com.

[tyxla]

LGTM, thanks 👍 🚀