Add QUOTE_IDENT function

Goal: Have a helper function in the util/Strings  to quote identifiers, which will enable proper quoting of protected keywords when used as identifiers.  This will help the fdbsqldump to properly create a backup when keywords are used as names. 

QUOTE_IDENT() will be available as a SQL function, as created in the QuoteIdent.java class. It provides quoting only if needed. It takes three arguments, String with the identifier, the quoting character, and a boolean as an option to always force quoting.