check and use new xlat_func_bare_words

check and use new xlat_func_bare_words

which changes the parsing of function arguments from

  * all unquoted arguments must be single-token bare words

to

  * all unquoted arguments are expressions

The default is to enable the flag, as there are a large
number of configuration files to update.

for now, the compatibility flag is disabled for src/tests/unit
and src/tests/xlat, and enabled for src/tests/keywords and
src/tests/modules