Just standardizing built-in extensions to use a `internal sealed class
Icons` for all their non-dynamic icons.
Looks like a LOT of changes, but it's icons all the way down.
I'm filing this so that I don't lose it on this machine I use less often. We can probably hold it out of 0.90
Fixes:
* If a package is installed, we always display the version as "Unknown"
* also deals with a case where getting the package metadata could fail, and we'd hide the list item. That's only possible in the "installed, no updates available" case
* Allow package updates, add an icon for updates
* moves off the preview winget API onto a higher stable version
**WARNING:** This PR will probably blow up all in-flight PRs
at some point in the early days of CmdPal, two of us created seperate
`Exts` and `exts` dirs. Depending on what the casing was on the branch
that you checked one of those out from, it'd get stuck like that on your
PC forever.
Windows didn't care, so we never noticed.
But GitHub does care, and now browsing the source on GitHub is basically
impossible.
Closes#38081
