Allow conhost to be replaced with OpenConsole

# Description of the new feature/enhancement

conhost can lack behind OpenConsole by several (if not many) years. This brings 2 problems:
* People preferring conhost's look and feel cannot get updates for many years.
* We (the maintainers) cannot test new features and changes for many years.

In other words, not being able to replace conhost is a lose-lose situation.

# Proposed technical implementation details (optional)

* Ship a conhost package in the store that replaces the system conhost, just like how notepad does it.
* Consider doing the same for the Windows Terminal Canary package so that we can get a slightly better usage coverage.

The issue proposes replacing the system conhost with a Store package and possibly doing the same for Windows Terminal Canary, but it names no files, tests, or entry points. Start by locating the existing conhost packaging and replacement behavior. Done means defining and implementing the packaging approach, with coverage for both proposed replacement scenarios.

Written by the indexing model from the issue text.