Don't require the callers to hold on to the source code string until an
eventual diagnostics code path is hit. Instead it turns out it's
simpler to let the parser consume the source code as string, where
internally after tokenizing it can be moved into the diagnostics and
from there into the code map if needed.
There are a few places where we now clone the source code, but that's
only in cases where we also extract stuff separately (test code) or the
syntax updater.
For a .60 files the locally defined components are now stored in a separate
per-document TypeRegistry instance that falls back to the global registry
for lookups.
This is relatively straight-forward via a pass in the compiler to
collect the resources to embed and then use include_bytes! (once per
resource).
What's really annoying is that the rust resource enum can't store a
&'static [u8] because cbindgen doesn't represent that, probably because
the slice representation isn't guaranteed to stay as it is. So instead
this, for now, uses raw pointers.
