Easier way to add support for more scalar functions during JDBC predicate pushdown

[aaneja]

Issue

During JDBC predicate pushdown, we parse the OperatorTranslators registry with the TranslatorAnnotationParser#parseFunctionDefinitions to build a Map<FunctionMetadata, MethodHandle>

These map is then used in FunctionMetadata#translate to check if the predicate expression will translate into a JdbcExpression

This approach works, but for every new scalar function (or variant with different type parameters), we would need to add a new method in the OperatorTranslators class.
For example, to support INTEGER addition, we would need to add the below method in OperatorTranslators -

@ScalarOperator(ADD)
@SqlType(StandardTypes.INTEGER)
public static JdbcExpression addInteger(@SqlType(StandardTypes.INTEGER) JdbcExpression left, @SqlType(StandardTypes.INTEGER) JdbcExpression right)
{
    return new JdbcExpression(infixOperation("+", left, right), forwardBindVariables(left, right));
}

This would need to be repeated for other type variants like DOUBLE, SMALLINT, TINYINT - which gets quite onerous

Change needed

Instead of using methods with Java annotations to build the Map<FunctionMetadata, MethodHandle> we need an easier way to support the common operators that should translate with most Jdbc backends