Improve .NET Shared Framework bundle installer accessibility (dotnet/core-setup#5549)

Improve .NET Shared Framework bundle installer accessibility (dotnet/core-setup#5549)

* Add missing 'Name' attributes to bundle installer

'Image' and 'Text' tags were missing 'Name' attributes.

* Shrink text bounds to fit inside parent

Fixes "An element's BoundingRectangle must be contained within its parent element."

* Fix tab stops: add links, remove text

Some links couldn't be navigated to, and some non-interactive text on the welcome screen could be focused.

Commit migrated from https://github.com/dotnet/core-setup/commit/28fb2967251f3d63cb8a9c82529f671836941bdd