Releases for macOS lack Apple Code Signing, executable bit

[kornelski]

Rust-analyzer is very tedious to install on macOS if not using VSCode's automation.

• It is not signed by Apple, which makes macOS freak out about it and flag it as malware unless the executable is launched first via a semi-hidden bypass method.

• .gz unarchives it as a text file called rust-analyzer-x86_64-apple-darwin, rather than an executable called rust-analyzer.

I suggest signing it (it unfortunately requires Apple Developer account, $99/year, and a macOS machine with a bunch of certificates set up).

I suggest distributing it as a tarball or zip that can set the right filename and executable bit (but please don't use dmg, this is a slow inefficient clunky format, and an overkill here).

[jonas-schievink]

This will probably have to wait until rust-analyzer is properly shipped with and installed through rustup, which will hopefully let us use the Rust project's signing infrastructure