Merge pull request #19850 from regexident/dyn-semantics

Add support for type-erased `Semantics<'db, dyn HirDatabase>`, by use of `DB: ?Sized`

Author: ChayimFriedman2

crates/hir/src/semantics.rs

@@ -147,7 +147,7 @@ impl TypeInfo {
 }
 
 /// Primary API to get semantic information, like types, from syntax trees.
-pub struct Semantics<'db, DB> {
+pub struct Semantics<'db, DB: ?Sized> {
     pub db: &'db DB,
     imp: SemanticsImpl<'db>,
 }