Replace contextMenus with menus

[caugner]

Description

Replace contextMenus with menus.

Motivation

Resolves webextallexamples flaws reported by @mdn/rari.

Additional details

See: https://caugner.github.io/mdn-flawless/#locale=en-US&templ=webextallexamples

Related issues and pull requests

Part of mdn/fred#1462.

See also:

• Replace webextapiref links for contextMenus content#44041
• Replace another webextapiref link for contextMenus content#44090

[Rob--W]

These examples use contextMenus, not the menus APIs.

Restating what I wrote at mdn/content#44090 (review) :

Although mdn only features "menus" without "contextMenus", we should really be documenting both instead of deleting references to contextMenus.

Sadly the same API is available under 2 namespaces, but different permissions.

contextMenus namespace + contextMenus permission

menus namespace + menus permission.

menus is available in Firefox and Safari, not Chrome.

contextMenus is available in all.

[rebloor]

@rebloor (note to self) when this is resolved, if we are retaining contextMenus, confirm that these examples show on menus.create and menus.onClicked (which they don't at the moment) and, if necessary, add links.