Multi-Block Election part 0: preparation and some cleanup. (#9442)

* Partially applied

* Everything builds, need to implement compact encoding as well.

* Fix some tests, add a ui test as well.

* Fix everything and everything.

* small nits

* a bunch more rename

* more reorg

* more reorg

* last nit of self-review

* Seemingly fixed the build now

* Fix build

* make it work again

* Update primitives/npos-elections/solution-type/src/lib.rs

Co-authored-by: Guillaume Thiolliere <gui.thiolliere@gmail.com>

* Update primitives/npos-elections/solution-type/src/lib.rs

Co-authored-by: Guillaume Thiolliere <gui.thiolliere@gmail.com>

* nits

* factor out double type

* fix try-build

Co-authored-by: Guillaume Thiolliere <gui.thiolliere@gmail.com>

substrate/Cargo.lock

@@ -9141,26 +9141,12 @@ dependencies = [
  "serde",
  "sp-arithmetic",
  "sp-core",
- "sp-npos-elections-compact",
+ "sp-npos-elections-solution-type",
  "sp-runtime",
  "sp-std",
  "substrate-test-utils",
 ]
 
-[[package]]
-name = "sp-npos-elections-compact"
-version = "4.0.0-dev"
-dependencies = [
- "parity-scale-codec",
- "proc-macro-crate 1.0.0",
- "proc-macro2",
- "quote",
- "sp-arithmetic",
- "sp-npos-elections",
- "syn",
- "trybuild",
-]
-
 [[package]]
 name = "sp-npos-elections-fuzzer"
 version = "2.0.0-alpha.5"
@@ -9175,6 +9161,20 @@ dependencies = [
  "structopt",
 ]
 
+[[package]]
+name = "sp-npos-elections-solution-type"
+version = "4.0.0-dev"
+dependencies = [
+ "parity-scale-codec",
+ "proc-macro-crate 1.0.0",
+ "proc-macro2",
+ "quote",
+ "sp-arithmetic",
+ "sp-npos-elections",
+ "syn",
+ "trybuild",
+]
+
 [[package]]
 name = "sp-offchain"
 version = "4.0.0-dev"