Sql prepared statements

[SunnysideAaron]

This PR is not ready for merging but I'm adding it in case anyone stumbles on it in the future.
#1 should be merged first.

This PR makes adjustments for prepared statements. passing values directly from urls into sql strings is very dangerous.

Left to do on this PR

• The MongoDB parser does return values but the strings returned need to be adjusted for MongoDBs parameterized queries format. I don't use MongoDB so I'm leaving that bit for others. Though I could take a stab at it if this PR ever gets close to merging.
• SQLs prepared statements format can be different based on the DB. "?" and "$1" off the top of my head but I'd have to look at the major players like sqlite, mysql, postgres, Microsoft SQL Server, Oracle, etc. Might make sense to have a way to pass that in or change. Since I'm using Postgres that is what I coded for.
• readme has to be adjusted for example custom operators

customOperators := []rsql.Operator{
    {
        Operator: "=ilike=",
        Formatter: func(key, value string, paramIndex *int) (string, []any) {
            *paramIndex++
            value = strings.ReplaceAll(value, "*", "%")
            return fmt.Sprintf(`%s ILIKE $%d`, key, *paramIndex), []any{value}
        },
    },
}