[Menu][Submenu]: Disabled menu item with submenu does not display correct visuals

[najikahalsema]

Description

When a menu item with a submenu is disabled, the chevron should also appear disabled.

Steps to reproduce

1. Go to Menu storybook
2. Inspect the submenu element in devtools and set disabled to "true"
3. Observe that while the text of the menu item is greyed out, the chevron remains "active".

Expected behavior

The chevron should be greyed out, too.

Screenshots

CSS storybook example

SWC storybook example

Live example on Webcomponents.dev

Environment

Chrome 116.0.5845.187 on Mac OS Ventura 13.5.2

Additional context

Reported by Stefan Puchta of PSWeb

[pfulton]

Tracking this issue in Jira: https://jira.corp.adobe.com/browse/CSS-594