fix: get foreground color from GtkMenuBar#menubar (3-0-x)

[Cobinja]

Description of Change

Backport of #15878 to 3-0-x
Depends on electron/libchromiumcontent#741
/cc @inukshuk

Checklist

• PR description included and stakeholders cc'd
• npm test passes
• PR title follows semantic commit guidelines

Release Notes

Notes: Fixes incorrect foreground color on GTK menubar

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[codebytere]

Just need to wait for #16245, then we'll get this merged!

[release-clerk]

Release Notes Persisted

Fixes incorrect foreground color on GTK menubar