Encode + in WebUI commands so it doesn't get lost #858

Job	Run time
build (ubuntu-latest, noradio)	2m 1s
tests (ubuntu-latest, tests)	28s
build (ubuntu-latest, wifi)	2m 27s
tests (macos-latest, tests)	28s
build (ubuntu-latest, bt)	2m 13s
tests (windows-latest, tests_nosan)	1m 26s
build (macos-latest, noradio)	1m 27s
build (macos-latest, wifi)	1m 45s
build (macos-latest, bt)	1m 49s
build (windows-latest, noradio)	4m 21s
build (windows-latest, wifi)	5m 24s
build (windows-latest, bt)	5m 46s
	29m 35s

Provide feedback