Fix handling of collation in SQL-language functions.

Fix handling of collation in SQL-language functions.

Ensure that parameter symbols receive collation from the function's
resolved input collation, and fix inlining to behave properly.

BTW, this commit lays about 90% of the infrastructure needed to support
use of argument names in SQL functions.  Parsing of parameters is now
done via the parser-hook infrastructure ... we'd just need to supply
a column-ref hook ...