[NNC] New APIs to get loops corresponding to a Buf (#53778)
Summary:
Fixes https://github.com/pytorch/pytorch/issues/53092
This PR adds the following APIs to NNC.
```
// In For:
static For* getParentLoop(const Stmt* st);
static std::vector<For*> getEnclosingLoopNest(const Stmt* st);
// In LoopNest:
std::vector<const Stmt*> getAllWritesToBuf(const Buf*) const;
std::vector<For*> getAllInnermostLoopsWritingToBuf(const Buf*) const;
std::vector<std::vector<For*>> getAllLoopNestsWritingToBuf(const Buf*) const;
```
These APIs are required for some usecases that involve multiple transformations like `splitWithTail` followed by `reorder` as shown in https://github.com/pytorch/pytorch/issues/53092
Pull Request resolved: https://github.com/pytorch/pytorch/pull/53778
Reviewed By: albanD
Differential Revision: D26987013
Pulled By: navahgar
fbshipit-source-id: 491459eddfff045132d2358631ad069bbcc520df
