Benchmarks run out of heap space in optimized JS

The benchmark test suite of Effekt Plots fails since a few days.

The culprits are two JS test cases that run out of heap space: `resume_nontail 10000` and `sum_range 10000000`. Both OOMs are reproducible with a maximum heap size of `2GiB` but not with `4GiB` (the default on MacOS). Since the tests are rather minimal and require maximally a few MiB on LLVM, this is in fact a problem of the JS backend.

To continue benchmarking on Effekt Plots, a **temporary** solution would be to increase the default heap size or, better, allow passing custom flags to the JS (+ LLVM) runner from the Effekt CLI, potentially via environment variable.

We have yet to determine the cause of the sudden change on plots, since no relevant code was changed and we cannot reproduce a working state on older versions.