[Kernel][Backend][Model] Blocksparse flash attention kernel and Phi-3-Small model (#4799)

Co-authored-by: beagleski <yunanzhang@microsoft.com>
Co-authored-by: bapatra <bapatra@microsoft.com>
Co-authored-by: Barun Patra <codedecde@users.noreply.github.com>
Co-authored-by: Michael Goin <michael@neuralmagic.com>

docs/source/models/supported_models.rst

@@ -123,6 +123,10 @@ Alongside each architecture, we include some popular models that use it.
     - Phi-3
     - :code:`microsoft/Phi-3-mini-4k-instruct`, :code:`microsoft/Phi-3-mini-128k-instruct`, etc.
     -
+  * - :code:`Phi3SmallForCausalLM`
+    - Phi-3-Small
+    - :code:`microsoft/Phi-3-small-8k-instruct`, :code:`microsoft/Phi-3-small-128k-instruct`, etc.
+    -
   * - :code:`QWenLMHeadModel`
     - Qwen
     - :code:`Qwen/Qwen-7B`, :code:`Qwen/Qwen-7B-Chat`, etc.