internal: Refactor load/store/compile implementation

This commit refactors the load/store/compile implementation that used
to live inside the runtime package. Specifically:

* Move init-time file loading logic into separate internal package
  (initload) along with store/compile logic. Add tests around
  load/store/compile that don't require the entire Runtime object.
  This also avoids duplication of the "version overwriting" logic.

* Move store/compile calls into the manager. This avoids the need for
  two compile operations on startup.

Signed-off-by: Torin Sandall <torinsandall@gmail.com>