Add Cesium ion geocoder to CesiumIonClient::Connection #3204

Job	Run time
Linting	11m 12s
Quick Checks	9s
Documentation	1m 4s
windows-2022 / Debug	22m 36s
ubuntu-22.04 / gcc / Debug	3m 45s
windows-2022 / RelWithDebInfo	22m 4s
ubuntu-22.04 / gcc / RelWithDebInfo	8m 7s
ubuntu-20.04 / clang / Debug	3m 51s
ubuntu-20.04 / clang / RelWithDebInfo	3m 40s
macos-13 / clang / Debug	7m 3s
macos-13 / clang / RelWithDebInfo	20m 7s
	1h 43m 38s

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