Add a Settings.parserJDBCEscapeSyntax

[lukaseder]

Our parser supports parsing JDBC escape syntax by default, which is a reasonable default for usage as a JDBC proxy (the ParsingConnection), but it might be undesired in other situations, e.g. when working with the ParserCLI from non-Java environments.

jOOQ 3.20 now supports the PostgreSQL ? operator that maps to jsonb_exists:

• Add support for the JSON_KEY_EXISTS() function #14827

Within JDBC, that operator has to be escaped as ??, see:

• https://jdbc.postgresql.org/documentation/query/#using-the-statement-or-preparedstatement-interface

As such, we'll parse both ? and ?? as valid operators when working with the JDBC escape syntax. ? is supported in static statements, and ?? only in prepared statements.

Other JDBC escape syntax will also be affected. The default flag value is true for backwards compatibility reasons.