5832.feat

Introduce the attributes {:isolate} and {:isolate "paths} that simplify the verification of an assertion by introducing additional verification jobs. {:isolate} can be applied to `assert`, `return` and `continue` statements. When using `{:isolate_assertions}` or `--isolate-assertions`, each return statement now creates a separate verification job for each ensures clause. Previously all ensures clauses where verified in a single job, for all return statements.