Rollup merge of #81277 - flip1995:from_diag_items, r=matthewjasper

Make more traits of the From/Into family diagnostic items

Following traits are now diagnostic items:
- `From` (unchanged)
- `Into`
- `TryFrom`
- `TryInto`

This also adds symbols for those items:
- `into_trait`
- `try_from_trait`
- `try_into_trait`

Related: https://github.com/rust-lang/rust-clippy/pull/6620#discussion_r562482587

compiler/rustc_span/src/symbol.rs

@@ -622,6 +622,7 @@ symbols! {
         intel,
         into_iter,
         into_result,
+        into_trait,
         intra_doc_pointers,
         intrinsics,
         irrefutable_let_patterns,
@@ -1159,6 +1160,8 @@ symbols! {
         truncf32,
         truncf64,
         try_blocks,
+        try_from_trait,
+        try_into_trait,
         try_trait,
         tt,
         tuple,