[WolfgangHG]

This resolves part two of https://github.com/orgs/wixtoolset/discussions/9313: it is not possible to update an extension. So you first have to remove the old version and then add the new version.

This pull request adds a wix extension update command: it removes all older (but no newer) versions of the extension from the extension cache, then it does the same as wix extension add ... would do.

Sample:

wix extension update -g "WixToolset.Util.wixext/7.0.0"

Is it required to check the version of the found extensions, or could I remove also newer version?

I marked this pull request as "draft" because I want to use the wix extension remove log message that I added in #734. If my suggestion to enhance logging from #734 is accepted, I would also add a similar status message to wix extension add.

Is there anything else that I need to update? Unit tests?

[WolfgangHG]

I thought about using ExtensionCacheManager.ListAsync to get a list of all installed versions of an extension, but this method internally loops over a list of cache locations, while AddAsync and RemoveAsync work on a single (the first) cache folder. So I fall back to checking the cache folder content myself.