Fix argument passing to scripts being interpreted with '#!' shebang lines

[anholt]

Description

I refactored script vs ELF handling as part of some ELF loading work I was doing, and it revealed that we were ignoring the original argv[] of a script that got interpreted based on its '#!' line. Add an integration test that passed on Linux and failed on kerla, and fix the bug.

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• Fixed all cargo clippy warnings.
• Applied rustfmt.

[nuta]

Good catch!