Make DeviceSettings.isEnhancedReadabilityModeEnabled available for Fenix 7 family of devices

The docs for isEnhancedReadabilityModeEnabled (https://developer.garmin.com/connect-iq/api-docs/Toybox/System/DeviceSettings.html#isEnhancedReadabilityModeEnabled-var) say that it's not available for fenix 7. `System.DeviceSettings has :isEnhancedReadabilityModeEnabled` returns `false` as well. I checked it for both simulator and the real device running firmware 17.23. 

However, more or less recent fenix 7 firmwares (17.23 included) seem to support "large fonts"/there's a setting in "System > Display > Large Fonts" (that indeed affects the font sizes for standard UI/glances).

As far as I can read it, the documentation for Connect IQ Core Topics (https://developer.garmin.com/connect-iq/core-topics/user-interface/) tells that isEnhancedReadabilityMode should be available in the above case, but it's not (for Fenix 7). That looks like a bug/inconsistency.

Enhanced Readability Mode

Since API level 4.2.0

Some devices have a new setting that enlarges the sizes of fonts in menus, glances and application pages to enhance readability. To add support for enhanced readability mode, check DeviceSettings.isEnhancedReadabilityMode at runtime to see if you should be using larger fonts. Implementing AppBase.onEnhancedReadabilityModeChanged() will let you know if the setting changed while the app was running.

Just in case, it's also known to work as expected for Forerunner 955 (both simulator and real devices).

I particularly need it to work correctly, because I want to make the glance view of my app to employ different fonts depending on the system setting, so that it would look aligned with the rest of the (standard) glances when Large Fonts are enabled. Just in case, I employ GLANCE_FONT for rendering text on the glance and it looks too small for the case when Large Fonts are enabled, hence I plan to use a bigger font in this case instead, relying on the setting value.