Update base for Update on "[ET-VK] 5/n Split dispatches between multiple command buffers. Track previously submitted command buffers in context and add function to execute all previous command buffers."

The diff adds changes to store command buffers submitted with final_use set to false.

Storing these buffers is necessary for `execute()` function. Since, `encode_execute()` function is typically called once but `execute()` can be called multiple times, `submit_all_non_final_cmds` function is added so all recorded command buffers with `final_use = False` can be called multiple times in `execute()`.

#### Key Changes
*   Added a flag `execute_pending_first_submission` to the `ComputeGraph` class to track whether execute nodes have been freshly encoded and need to be submitted first.
*   Added a new function `submit_all_non_final_cmds` to the `Context` class, which submits all non-final command buffers to the GPU.
*   Modified the `submit_cmd_to_gpu` function to add the submitted command buffer to the `non_final_cmds_` list if it's not marked as final use.
*   Updated the `execute` function in `ComputeGraph` to submit all non-final command buffers before executing the graph.

Differential Revision: [D78360038](https://our.internmc.facebook.com/intern/diff/D78360038/)

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Author: trivedivivek