[hwasan] Add testcase for check-memaccess when using a fixed shadow (#89328)

The test case is based on hwasan-check-memaccess.ll (albeit updated
using update_llc_test_checks) with --hwasan-mapping-offset=...

--hwasan-mapping-offset=... actually doesn't affect the LLVM IR at the
moment; future work will introduce memaccess fixed shadow intrinsics.
(https://github.com/llvm/llvm-project/pull/89319)