JDBC 4.5 support: Firebird-specific implementation of various enquote methods on Connection

[mrotteveel]

JDBC 4.5 adds the following methods to Connection:

• default String enquoteIdentifier(String identifier, Boolean alwaysQuote) throws SQLException
• default String enquoteLiteral(String val) throws SQLException
• default String enquoteNCharLiteral(String val) throws SQLException
• default boolean isSimpleIdentifier(String identifier) throws SQLException

The default implementation is not sufficient for Firebird (especially dialect 1); move the implementation of the equivalent methods from FBStatement to connection, and make statement call the implementation on FBConnection (NOTE: we may also need to move those overridden methods from FBStatement to AbstractStatement for correctness).

[mrotteveel]

The existing implementation in FBStatement needs some further refinement when we move it to FBConnection. For example, the default implementation in JDBC 4.5 considers SQL:2003 reserved words to not be simple identifiers and our current implementation only considers the basic syntax rules to determine if an identifier is simple or not. Another example is that we currently consider identifiers enclosed in double quotes already correctly quoted, instead we should remove the enclosing quotes, and unescape (undouble) double quotes (if any) and quote/escape the identifier again (in case the provided identifier was not correctly escaped or contains invalid characters, see next). We probably also should add the "invalid character" check similar to the default implementation in Java 26 (i.e. disallow \u0000, and maybe some other unprintables).

To be able to improve the simple identifier check, we will need to add reserved words for all supported versions to the FirebirdVersionMetaData enum (or maybe the FirebirdReservedWords enum so it is also available for the parser, and reference that from FirebirdVersionMetaData).