Sign Mac .pkg

[benarent]

What happened:
When trying the new .pkg, I get a message that it's from an unidentified developer. We should consider adding a developer ID to the pkg. https://developer.apple.com/developer-id/

What you expected to happen:
It'll make gatekeeper a little happier, and won't require people to log into settings to open the app.

We've a few extra steps to signup as an org, https://developer.apple.com/programs/enroll/ but afterwards the process looks pretty simple and we could add to the build process.

[benarent]

@webvictim we chatted about this on the on-site. Not sure of our current process but if you want to get started I'll work with @twakes to obtain a Apple Org account.

[webvictim]

I think I never noticed this during testing because I did the whole thing in a terminal with something like sudo installer -pkg /path/to/package.pkg -target /...

I agree we should definitely get a certificate and sign these though.

[webvictim]

This work is done, at least for tsh.

Signed packages will be coming out with Teleport 4.2.1.

[webvictim]

Signed and notarized client-only tsh packages are now available - https://get.gravitational.com/tsh-4.2.1.pkg

This should make the experience on MacOS Catalina much nicer. The package URL is the same for both OSS and Enterprise versions of Teleport, as the tsh client does not change between the two.

We should be able to expand this support to providing signed/notarized teleport packages for MacOS when we resolve #3158. For now though, I'm going to close this issue.