Get rid of `rustc_query_description!`

Get rid of `rustc_query_description!`

Queries can provide an arbitrary expression for their description and
their caching behavior. Before, these expressions where stored in a
`rustc_query_description` macro emitted by the `rustc_queries` macro,
and then used in `rustc_query_impl` to fill out the methods for the
`QueryDescription` trait.

Instead, we now emit two new modules from `rustc_queries` containing the
functions with the expressions. `rustc_query_impl` calls these functions
now instead of invoking the macro.

Since we are now defining some of the functions in
`rustc_middle::query`, we now need all the imports for the key types
there as well.