Implement full content edit for preview

Implement full content edit for preview

This change contains a full language, structure, and style edit for
the preview content that has been copied from TD to Git.
The purpose of this change is to match the quality and style of the
preview content to that of the rest of the Tizen library.

The Getting Started section has been restructured, since it seems
that there are actually 3 different scenarios: creating a new
project, creating a new project with a cross-platform solution, and
porting an existing cross-platform solution to Tizen.

PS2: Added the What's New section changes from TD
PS3: Installation topic has been rewritten based on a trial installation
PS4: Rebase
PS5: Redid some images on a Windows 10 machine, redid emulator
     screenshot.
PS6: Implemented responses to queries.
PS7: Removed profile icons and profile info from dependencies.
     Moved the API Checker topic within the TOC to reflect the TD.
     Modified the What's New topic based on the latest TD changes.
     Minor style fixes in the Installation topic.
     Modified oversized roadmap image.
PS8: Minor terminology, grammar, and tagging fixes
     Changed "Tizen Platform-Specific API" to "TizenFX API"
PS9: Changed 1 more instance to "TizenFX API"
PS10: Fixed "TizenFX API" term in an image.

Change-Id: I6c24b7efb98b792c3fb3d46320412c1e3ff77701