Auto merge of #54088 - matthewjasper:use-reason-in-dlle-errors, r=pnkfelix

[NLL] Suggest let binding

Closes #49821

Also adds an alternative to `explain_why_borrow_contains_point` that allows changing error messages based on the reason that will be given. This will also be useful for #51026, #51169 and maybe further changes to does not live long enough messages.

src/test/ui/issues/issue-36082.ast.nll.stderr

@@ -8,6 +8,8 @@ LL |     let val: &_ = x.borrow().0;
 ...
 LL |     println!("{}", val);
    |                    --- borrow later used here
+   |
+   = note: consider using a `let` binding to create a longer lived value
 
 error: aborting due to previous error
 

src/test/ui/issues/issue-36082.mir.stderr

@@ -8,6 +8,8 @@ LL |     let val: &_ = x.borrow().0;
 ...
 LL |     println!("{}", val);
    |                    --- borrow later used here
+   |
+   = note: consider using a `let` binding to create a longer lived value
 
 error: aborting due to previous error
 

src/test/ui/issues/issue-36082.rs

@@ -28,6 +28,7 @@ fn main() {
     //[mir]~^^^^^ ERROR borrowed value does not live long enough [E0597]
     //[mir]~| NOTE temporary value does not live long enough
     //[mir]~| NOTE temporary value only lives until here
+    //[mir]~| NOTE consider using a `let` binding to create a longer lived value
     println!("{}", val);
     //[mir]~^ borrow later used here
 }