Moving NposSolution to frame (#11031)

* Move `sp-npos-elections-solution-type`
to `frame-election-provider-support`
First stab at it, will need to amend some more stuff

* Fixing tests

* Fixing tests

* Fixing cargo.toml for std configuration

* fmt

* Committing suggested changes
renaming, and re exporting macro.

* Removing unneeded imports

* Move `NposSolution` to frame

* Removing `npos_election` dependencies
Implementing _fpes better

* some feedback for moving NPoSSolution to frame

* fmt

* more formatting

* Fixed some imports and fmt

* Fixing docs

Co-authored-by: kianenigma <kian@parity.io>

substrate/primitives/npos-elections/src/lib.rs

@@ -100,26 +100,16 @@ pub mod pjr;
 pub mod reduce;
 pub mod traits;
 
-pub use assignments::{Assignment, IndexAssignment, IndexAssignmentOf, StakedAssignment};
+pub use assignments::{Assignment, StakedAssignment};
 pub use balancing::*;
 pub use helpers::*;
 pub use phragmen::*;
 pub use phragmms::*;
 pub use pjr::*;
 pub use reduce::reduce;
-pub use traits::{IdentifierT, NposSolution, PerThing128, __OrInvalidIndex};
+pub use traits::{IdentifierT, PerThing128};
 
-// re-export for the solution macro, with the dependencies of the macro.
-#[doc(hidden)]
-pub use codec;
-#[doc(hidden)]
-pub use scale_info;
-#[doc(hidden)]
-pub use sp_arithmetic;
-#[doc(hidden)]
-pub use sp_std;
-
-/// The errors that might occur in the this crate and solution-type.
+/// The errors that might occur in this crate and `frame-election-provider-solution-type`.
 #[derive(Eq, PartialEq, RuntimeDebug)]
 pub enum Error {
 	/// While going from solution indices to ratio, the weight of all the edges has gone above the