Allows using meta.jl much earlier in the build (instead of importing
these from show.jl).

Manual `gensym` code often contains a lot of mistakes, either because
the user uses something like `.` or `+`, or because it combines code
from multiple modules (gensym is only unique within a pre-compile unit).
This replaces most uses for macro local variables with proper scope
markers, and checks for those markers correctly when doing replacements.
I did not fully rewrite `_lift_one_interp_helper` or
`replace_ref_begin_end_` however, since, while possible by adding `esc`
to every argument that has not used a gensym value, if any other
argument did is a value, I worried that could lead to macroexpand.scm
making more new mistakes so I left if for a separate PR. Better yet, we
could make a unhygienic-scope and unescape pair for marking the
inverse/dual of the usual operations (marking a symbol as unescaped
within a region of unhygienic (escaped) code to make these various uses
easier to implement.

But rewrite `replace_ref_begin_end_` to respect argument order and
evaluation count (similar to its julia-syntax.scm counterpart) and
scoping (not adding `let` unpredictably). This required also rewriting
`gen_call_with_extracted_types` to properly support the ways that
might require rewriting the expression, particularly against the new
`::` syntax support in the interactive macros.