[FEATURE REQUEST] Provide prebuilt binaries for each target triples

[5d-jh]

What
Provide librdkafka and its bindings as binary on release assets. Like swc-project.

Why
To speed up postinstall operation and avoid tackle with compilation errors/warnings.

How
When merged into master branch, compile native code and publish onto releases page.

Add postinstall script to download binary for suitable platform, using prebuild-install cli.

[jsumners-nr]

It'd be better to use prebuildify. A post install script to download binaries from a web site is not a great experience.

See newrelic/node-native-metrics#238 for one such conversion.