Avoid mixing `isabelle`, `make`, and `run_tests` invocations. Standardise on `run_tests` and mention `L4V_ARCH` each time to indicate that you can and should set `L4V_ARCH`. Signed-off-by: Gerwin Klein <gerwin.klein@proofcraft.systems>
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Hooked up into build system and regression test; added READMEs