[CK_TILE] Stream-K Tree Reduction and Cache Skipping Integration (#3371)

* CK Tile Stream-K Tree Reduction

This change adds the first implementation of the Stream-K tree reduction
strategy into CK Tile. The tree reduction reduces the the number of
steps for accumulating results for a tile from O(N) to O(logN) where N
is the number of workgroups contributing to a C tile.

Additionally, in the original non-atomic reduction strategy, atomics
were used to set the flags buffer and to read from the flags buffer.
Howeover, through investigation with the tree reduciton, atomics with
default (relaxed) semantics were not enough to guarantee workgroups
would not read stale data, leading to incorrect results. Stronger
acquire/release memory orderings are too expensive. So, this change
also eliminates the use of atomics for setting the flags. Instead, we
leverage cache modifiers (e.g., GLC) to avoid writing to cache, thereby
avoiding the use of atomics.

Prelimiary tests were also added for the normal reduction and tree
reduction. More will be added in a future PR via tile engine.

* Move Stream-K kernel files to a subdirectory

* Cleanup Code Style & Handle Unsupported Reductions

This change makes the following small changes:
- Add an explicit else block for unimplemented reduction strategies
- Clarify type of sk_flags_ptr via auto*
- Add description for extra_iters_before_me variable

* Run new copyright script on new files

include/ck_tile/ops/common/streamk_common.hpp

@@ -8,7 +8,8 @@
 namespace ck_tile {
 enum StreamKReductionStrategy : uint32_t
 {
-    Atomic    = 0u,
-    Reduction = 1u
+    Atomic        = 0u,
+    Reduction     = 1u,
+    TreeReduction = 2u
 };
 } // namespace ck_tile