Make Database Parameters more flexible

Currently, database parameters are hardcoded values that are based on instance memory. However, AWS supports using formulas to dynamically set these values based on instance properties ([docs](https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER_ParamValuesRef.html)). This way, if an instance resizes, database parameters scale with the instance. It would be good for us to make use of these formulas to make more flexible parameters.

However, this comes with challenges as we base parameters on other parameters. The formulas supported by AWS must be simple (only a single division or multiplication, nothing like `{DBInstanceClassMemory/1024/8/4}`. As such, we may need to figure out a way to parse the formulas to understand their meaning and then build dependent formulas based on those meanings.