Clean up SettingsGroup name and settingsGroup

src/Settings/AppSettings.cc

src/Settings/AppSettings.h

src/Settings/AutoConnectSettings.cc

src/Settings/AutoConnectSettings.h

src/Settings/BrandImageSettings.cc

src/Settings/BrandImageSettings.h

src/Settings/FlightMapSettings.cc

src/Settings/FlightMapSettings.h

src/Settings/GuidedSettings.cc

src/Settings/GuidedSettings.h

src/Settings/RTKSettings.cc

src/Settings/RTKSettings.h

src/Settings/SettingsGroup.cc

src/Settings/SettingsGroup.h

src/Settings/UnitsSettings.cc

src/Settings/UnitsSettings.h

src/Settings/VideoSettings.cc

src/Settings/VideoSettings.h

src/api/QGCCorePlugin.h