[9.x] Add toFullSql Method To Builder

[mrbugminer]

This pull request is add new "toFullSql" method to "Builder".

This method return full SQL query with all bindings replaced in query.

[BrandonSurowiec]

I think this is an awesome addition. There were two other attempts that were previously closed (maybe more.) Does this PR address any of the concerns with PostgreSQL that were raised?

#39551
#38027

[bert-w]

This needs tests for all supported SQL grammars :)

[taylorotwell]

Thanks for your pull request to Laravel!

Unfortunately, I'm going to delay merging this code for now. To preserve our ability to adequately maintain the framework, we need to be very careful regarding the amount of code we include.

If possible, please consider releasing your code as a package so that the community can still take advantage of your contributions!

If you feel absolutely certain that this code corrects a bug in the framework, please "@" mention me in a follow-up comment with further explanation so that GitHub will send me a notification of your response.