Detect generic type as type param and issue appropriate suggestions (#147889)

[maplethecolor]

Fixes #147889
The PR doesn't exactly match the original issue (w.r.t the second suggestion), so please provide input on which option is better. :)

[rustbot]

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[rust-log-analyzer]

The job aarch64-gnu-llvm-20-1 failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

diff of stderr:

- error[E0118]: no nominal type found for inherent implementation
-   --> $DIR/wrong-normalization.rs:16:1
+ error: expected one of `#`, `>`, `const`, identifier, or lifetime, found `{`
+   --> $DIR/wrong-normalization.rs:16:10
3    |
4 LL | impl <I8<{i8::MIN}> as Identity>::Identity {
-    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ impl requires a nominal type
-    |
-    = note: either implement a trait on it or create a newtype to wrap it instead
+    |          ^ expected one of `#`, `>`, `const`, identifier, or lifetime
8 
9 error: aborting due to 1 previous error
10 

- For more information about this error, try `rustc --explain E0118`.
12 

Note: some mismatched output was normalized before being compared
-   --> /checkout/tests/ui/const-generics/wrong-normalization.rs:16:10
+ error: expected one of `#`, `>`, `const`, identifier, or lifetime, found `{`
+   --> $DIR/wrong-normalization.rs:16:10
+    |          ^ expected one of `#`, `>`, `const`, identifier, or lifetime


The actual stderr differed from the expected stderr
To update references, rerun the tests and pass the `--bless` flag
To only update this specific test, also pass `--test-args const-generics/wrong-normalization.rs`

error: 1 errors occurred comparing output.
status: exit status: 1
command: env -u RUSTC_LOG_COLOR RUSTC_ICE="0" RUST_BACKTRACE="short" "/checkout/obj/build/aarch64-unknown-linux-gnu/stage2/bin/rustc" "/checkout/tests/ui/const-generics/wrong-normalization.rs" "-Zthreads=1" "-Zsimulate-remapped-rust-src-base=/rustc/FAKE_PREFIX" "-Ztranslate-remapped-path-to-local-path=no" "-Z" "ignore-directory-in-diagnostics-source-blocks=/cargo" "-Z" "ignore-directory-in-diagnostics-source-blocks=/checkout/vendor" "--sysroot" "/checkout/obj/build/aarch64-unknown-linux-gnu/stage2" "--target=aarch64-unknown-linux-gnu" "--check-cfg" "cfg(test,FALSE)" "--error-format" "json" "--json" "future-incompat" "-Ccodegen-units=1" "-Zui-testing" "-Zdeduplicate-diagnostics=no" "-Zwrite-long-types-to-disk=no" "-Cstrip=debuginfo" "--emit" "metadata" "-C" "prefer-dynamic" "--out-dir" "/checkout/obj/build/aarch64-unknown-linux-gnu/test/ui/const-generics/wrong-normalization" "-A" "unused" "-W" "unused_attributes" "-A" "internal_features" "-A" "unused_parens" "-A" "unused_braces" "-Crpath" "-Cdebuginfo=0" "-Lnative=/checkout/obj/build/aarch64-unknown-linux-gnu/native/rust-test-helpers"
stdout: none
--- stderr -------------------------------
error: expected one of `#`, `>`, `const`, identifier, or lifetime, found `{`
##[error]  --> /checkout/tests/ui/const-generics/wrong-normalization.rs:16:10
   |
LL | impl <I8<{i8::MIN}> as Identity>::Identity {
   |          ^ expected one of `#`, `>`, `const`, identifier, or lifetime

error: aborting due to 1 previous error
------------------------------------------

---- [ui] tests/ui/const-generics/wrong-normalization.rs stdout end ----