Add responsive footer icon
Port of: patchdemo@de8148aa
See MediaWiki core change: https://gerrit.wikimedia.org/r/c/mediawiki/core/+/1113827 (5cbf7ef06c2ed2d8e9ff4b679911ab73cb216d1e)
And a similar Wikimedia config patch: https://gerrit.wikimedia.org/r/c/operations/mediawiki-config/+/1121098 (832ce5167e195263004976e18e296b708544319b)