When peg/replace or peg/replace-all are given a function to serve as the text
replacement, any captures produced by the PEG are passed as additional
arguments to that function.
Functions will be invoked with the matched text, and their result will be
coerced to a string and used as the new replacement text.
This also allows passing non-function, non-byteviewable values, which will be
converted into strings during replacement (only once, and only if at least
one match is found).
This commit adds support for using & _ syntax to bind the remaining
values in an array in the match macro.
The commit also adds a few tests for the new syntax in suite0008
