MSTeams recipe to support the new MS Teams

[apettinen]

As Microsoft has launched the new, non-electron based Teams.app, the current MSTeams recipe requires some changes. Most notably, the MSTeamsURLProvider.py likely becomes obsolete for Mac, as Microsoft provides a static download URL on their Teams webpage, see https://www.microsoft.com/en-us/microsoft-teams/download-app -> Download new teams.

However, Windows seemingly does not have a static download link. Therefore, removing the MSTeamsURLProvider might be a breaking change.

Thus we have two options:

1. Make the the current recipe MS Teams Classic (breaking change too) and create a new one
2. Extend the MSTeamsURLProvider so that it will always offer the static download link for macOS. This is fairly simple change to do, plus additionally the code could be updated a bit (to be more Python3, for example).

Any comments on this, anyone?

[patgmac]

As-is today, your recipe is downloading the right thing, it's just failing when trying to read the Info.plist because the path has changed. I think updating the download recipe with the updated paths would be a quick fix for now.

[Bretterteig]

I'd prefer the second proposal. It is always good to keep recipes working. Especially because this recipe will be used a lot.
Additionally for migration purposes we could add a new input variable to switch between classic/new teams or rather make more use of MSTEAMS_PLATFORM to add osx-new or sth (with code added to the shared processor)