Moved deprecation of SQLQuery to 4.0

This PR replaces https://github.com/silverstripe/silverstripe-framework/pull/3630, but is targetting the 3 branch (aliased as 3.2).

The difference between this and the original PR is that SQLSelect has NOT been un-implemented, but rather the deprecation has been moved to 4.0, meaning that users upgrading from 3.1 to 3.2 won't automatically encounter any api deprecation issues.

I've also dropped the deprecation notices on the `sql(&$arguments)` method where no argument was given. The methods no longer fail simply because an argument is omitted, since they really should work fine without it.

The method signature for DataExtension::augmentSQL has been reverted back to the 3.1 compatible version, meaning less breakages for other upgrades from 3.1.

This PR is going to have to be manually and carefully merged up into 4.0, since we don't want to remove SQLQuery until 5.0, but it shouldn't be referenced anywhere, and augmentSQL should be changed in 4.0 anyway.