Option to control driver data return decoding strategy

[bombillazo]

Is your feature request related to a problem? Please describe.

Currently, the deno-postgres driver is hardcoded to parse values to JS types wherever possible and return strings where the parsing/decoding is not implemented. There is no way to opt out of this behavior if developers want to handle parsing in their applications.

Describe the solution you'd like

Have a Client option that allows users to set the parse mode to string or auto

• string : all values are returned as string, and the user has to take care of parsing
  auto : deno-postgres parses the data into JS objects (as many as possible implemented Add missing postgres types mapping / decoders / parser #446, non-implemented parsers would still return strings)

Both modes are overridable with some API to pass custom parser per oid type, giving users complete power over how they want any data type to be parsed by the library. (#239)

Describe alternatives you've considered

Directly changing the package source code in my application to override the behavior.

Additional context

N/A