Rollup merge of rust-lang#131163 - JakenHerman:master, r=Nadrieril

Add `get_line` confusable to `Stdin::read_line()`

This pull request resolves rust-lang#131091

---

I've updated tests for `tests/ui/attributes/rustc_confusables_std_cases` in order to verify this change is working as intended.

Before I submitted this pull request, I had a pull request to my local fork. If you're interested in seeing the conversation on that PR, go to JakenHerman#1.

---

**Testing**:
Run `./x.py test tests/ui/attributes/rustc_confusables_std_cases.rs`

std/src/io/stdio.rs

@@ -394,6 +394,7 @@ impl Stdin {
     ///   in which case it will wait for the Enter key to be pressed before
     ///   continuing
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_confusables("get_line")]
     pub fn read_line(&self, buf: &mut String) -> io::Result<usize> {
         self.lock().read_line(buf)
     }