Encode + in WebUI commands so it doesn't get lost #862

Job	Run time
build (ubuntu-latest, noradio)	2m 0s
build (ubuntu-latest, wifi)	2m 24s
tests (ubuntu-latest, tests)	28s
build (ubuntu-latest, bt)	2m 6s
tests (macos-latest, tests)	43s
build (macos-latest, noradio)	2m 22s
tests (windows-latest, tests_nosan)	1m 21s
build (macos-latest, wifi)	1m 55s
build (macos-latest, bt)	2m 15s
build (windows-latest, noradio)	4m 28s
build (windows-latest, wifi)	6m 25s
build (windows-latest, bt)	4m 37s
	31m 4s

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