MiniSet/MiniMap moved and renamed into SsoHashSet/SsoHashMap

It is a more descriptive name and with upcoming changes
there will be nothing "mini" about them.

compiler/rustc_data_structures/src/sso/mod.rs

@@ -0,0 +1,5 @@
+mod map;
+mod set;
+
+pub use map::SsoHashMap;
+pub use set::SsoHashSet;