Fix a few dependency edges, reinstate LowCProvider and its tests, provide a proper test target
Fix a few dependency edges, reinstate LowCProvider and its tests, provide a proper test target

mitls/hacl-star,mitls/hacl-star,mitls/hacl-star,mitls/hacl-star,mitls/hacl-star,mitls/hacl-star,mitls/hacl-star,mitls/hacl-star,mitls/hacl-star