windowMenu: Add context to screenshot action

windowMenu: Add context to screenshot action

The string "Take Screenshot" is used both by the action in the
window menu and the screenshot/recording toggle in the UI.

However in some languages, it would be best to use different
strings for the two use cases.

Address this by adding context to the window menu string, so
it can be differentiated from the string in the screenshot UI.

Closes: https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/7979
Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/3503>