fix(sem): analysis considers nested noreturn

[saem]

Summary

No-return analysis ensures that nested final expressions (
block/case/if/try ) are accounted for no-return itself.

Details

Prior to this change if the last expression within a greater expression
was a no-return expression it would not be deemed as such if it was a
block/case/if/try , instead errors would be raised related to discard
checks or that path not resulting in the correct type.

For example, the following would result in an error where 0 must be
used or discarded:

proc foo() =
  let x =
    if false: 10
    else:
      block:
        return

Fixes #1440

[saem]

/merge

[github-actions]

Merge requested by: @saem

Contents after the first section break of the PR description has been removed and preserved below:

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Notes for Reviewers

• it's cleaner than I thought
• let me know if there is a better module to use than ast_query, trees didn't seem right