Internal lint: check if `span_lint_and_then` and `span_*` are collapsable

[JohnTitor]

When span_lint_and_then and span_* have the same span, we can replace them with span_lint_and_* in most cases. It'd be nice that we have an internal lint for this.
It's a follow-up for this comment.

[flip1995]

Also only if the db.span_* is the only Expr/Stmt in the closure of span_lint_and_then.