Common code across large numbers of functions

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**Description**
There are scenarios where customers apply libraries across a large numbers of functions. Examples include custom SDKs, custom runtimes, or extensions. Today, these libraries must be managed on a per-function basis. There's no easy way to enforce or track their use. And if the library needs to be updated, you need to update each function individually. That becomes increasingly difficult as the number of functions scales, and ownership of those functions becomes distributed.

This feature is to enable common libraries to be deployed and managed at scale, across large numbers of functions, without a per-function management overhead.