Right now we always build the library before any apps.
Apps are where our syntax sugar translators (sigils, calls, braces) live.
So we can't use sugar in the standard library.
New idea: move all code for SubX phases into the top-level.
Perhaps we should also just build a single file rather than pipeline stages.
But for now we'll build each phase by building up to some specific layer.
This will simplify test_apps and move lots of one-off logic to a more standard
form in test_layers.
I'm also going to reorg existing layers so that we introduce each phase
at a point where it mostly only gets the helpers it needs.
This commit itself is just cleaning up some common strings. Using explicit
names for them streamlines binaries a bit.
