Ship corresponding version of base library with Motoko compiler so that it's always available by default?

[rvanasa]

The idea here is to bundle the corresponding version of the Motoko base library with the compiler as a default import for mo:base (or a different custom import) with an opt-out CLI flag. This would reduce the occurrence of errors which arise from mismatches in RTS / prim functions due to outdated package config files.

• Pro: Simplified developer experience (no need to install a package manager for basic Motoko programs)
• Con: More opinionation towards the official base library

This is one possible solution to #18.