Include the raw query string for the custom parser

#### Support plan

* *is this issue currently blocking your project?* (yes/no): no
* *is this issue affecting a production system?* (yes/no): no

#### Context

* *node version*: 14
* *module version*: 19
* *environment* (e.g. node, browser, native): node
* *used with* (e.g. hapi application, another framework, standalone, ...): hapi
* *any other relevant information*: using qs for query string parsing

#### What problem are you trying to solve?

I would like to send complex data in the query string. This includes nulls. The current preprocessing of the querystring will turn null objects properties into empty strings. More details and examples can be found here: https://github.com/ljharb/qs#handling-of-null-values

Currently the work around is to dig into the raw request in the handler and pull out the url and parse it myself. It would be nice if there was a second parameter on the custom parser to pass in the raw query string with no preprocessing done to it.

#### Do you have a new or modified API suggestion to solve the problem?
Test and working if you would like I can PR it.
https://github.com/efbenson/hapi/commit/5903cd510bc2dd47d3289e2089f2838fb9a9df27