This gets us two commits of interest:
- Replace within-module eval with hygienic eval: which makes it possible
  to include StyledStrings in the sysimage without running into
  precompile errors.
- Load the JULIA_*_COLOR env vars for compat: which mirrors the current
  behaviour to the relevant faces.

By loading the StyledStrings stdlib in REPL, we load the privateered
print/show methods for the Annotated{String,Char} types defined there.

This is nice to have, because it means that styled annotated strings can
be constructed in Base and elsewhere without loading the StyledStrings
stdlib, but they will be displayed as intended in the REPL.