Change default webMode to "tv"

[mseeley]

This PR changes the default layout to "tv", from Desktop. This change has already been made in our v3 preview builds.

Expected behavior

Previous to this change the default webMode was "desktop". On first run PMP creates plexmediaplayer.conf using the configuration defined in settings_description.json. With this in mind any PMP installations which have been run at least once will experience no change to the layout displayed on last run.

Existing installations, once updated to a version with this change, will change their webMode when one of the following happens:

• delete plexmediaplayer.conf
• reset webMode to default - SettingsComponent::resetToDefault
• reset all settings to default - SettingsComponent::resetToDefaultAll

Fresh installations not covered above will default webMode to "desktop".

Steps to test

• Download and run the 2.5.3 release.
  • Change to Desktop mode using UI.
• Exit 2.5.3
• Run the test build of this branch.
  • The app should remain in Desktop mode.
• Exit test build
• Delete plexmediaplayer.conf - ~/Library/Application\ Support/Plex\ Media\ Player/plexmediaplayer.conf
• Run test build
• App should launch in TV mode.

[mseeley]

@pcalves I've tried to trigger a test build of this branch in https://github.com/plexinc/plex-media-player/tree/dist-matt-tv-default-webMode. The force may not be strong enough with me.

[pcalves]

Triggered a build by hand in Jenkins: https://nightlies.plex.tv/plexmediaplayer/dist-matt-tv-default-webMode/2.53.0.1060-cff90758/

[mseeley]

Thanks @pcalves!