[Feature Request][compiler-v2] Dead store elimination optimization algorithm should be enhanced to eliminate cycles

[vineethk]

🚀 Feature Request

When there are cycles in the dead store elimination graph, (like between a = b and b = a in the loop below), we should be able to eliminate it.

module 0xc0ffee::m {
    public fun test(x: u64, a: u64, b: u64) {
        let i = 0;
        while (i < x) {
            a = b;
            b = a;
            i = i + 1;
        }
    }
}

This test case is tracked as variable-coalescing/cyclic_dead_store.move.