This PR prevents `try` swallowing heartbeat errors from nested `simp`
calls, and more generally ensures the `isRuntime` flag is propagated by
`throwNestedTacticEx`. This prevents the behavior of proofs (especially
those using `aesop`) being affected by the current recursion depth or
heartbeat limit.
This breaks a single caller in Mathlib where `simp` uses a lemma of the
form `x = f (g x)` and stack overflows, which can be fixed by
generalizing over `g x`.
Closes#7811.
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Co-authored-by: Sebastian Ullrich <sebasti@nullri.ch>
