Rollup merge of #108609 - clubby789:e0599-highlight, r=estebank

Highlight whole expression for E0599

Fixes #108603

This adds a secondary label to highlight the whole expression leading to the error. It also prevents empty labels being recognised as 'unexpected' by compiletest - otherwise, tests with NOTE annotations would pick up empty labels.

`@rustbot` label +A-diagnostics

Author: matthiaskrgr