Move aliased_io into AliasInfo.

[wujingyue]

This makes getOutputAlias easier to use. This will eventually help #1669 represent outputs that require evaluation but are not an alias. For that, we'll need to

1. Rename Alias* to Allocation*.
2. Rename AllocationType::PointerArithmetic to AllocationType::Evaluate.
3. When a MmaOp segment needs ATen evaluation, set its output allocation to .type=AllocationType::Evaluate,aliased_io=nullptr.

[wujingyue]

!build

[Priya2698]

This makes getOutputAlias easier to use. This will eventually help #1669 represent outputs that require evaluation but are not an alias. For that, we'll need to

1. Rename Alias* to Allocation*.
2. Rename AllocationType::PointerArithmetic to AllocationType::Evaluate.
3. When a MmaOp segment needs ATen evaluation, set its output allocation to .type=AllocationType::Evaluate,aliased_io=nullptr.

Are these changes supposed to be in future PRs?

[wujingyue]

Yes

[Priya2698]

LGTM.

[wujingyue]

!build