Auto merge of #110041 - fmease:diag-sugg-adding-const-param, r=compiler-errors

Suggest defining const parameter when appropriate

Helps a bit with #91119.
Following #105523's lead, I use placeholder `/* Type */` instead of `_` in the suggestion.
It should be easier for newcomers to parse.

`@rustbot` label A-diagnostics
r? diagnostics

Author: bors