desugar: Look through ticks when warning about possible literal overflow

Enabling `-fhpc` or `-finfo-table-map` would case a tick to end up
between the appliation of `neg` to its argument. This defeated the
special logic which looks for `NegApp ... (HsOverLit` to warn about
possible overflow if a user writes a negative literal (without out
NegativeLiterals) in their code.

Fixes #21701