ship known-compatible per-platform tier binaries in sdk package

[isaacs]

It'd be nice to not have to install multiple things when using the node SDK. Just ship a binary for each of the supported platforms, and expose the appropriate one as the bin. Then instead of starting the sidecar by calling tier and letting the path figure it out, start the one we know we're compatible with.

[isaacs]

Revive the @tier.run/tier-<platform>-<arch> optional deps once the binary updates slow down a bit. Maybe also explore automatically publishing new versions of these every time there's a golang bin release.