[Executorch] Make module constructors uniform across

[kimishpatel]

Stack from ghstack (oldest at bottom):

• [Executorch][LLM] Use caching allocator for runner #15730
• -> [Executorch] Make module constructors uniform across #15729
• [Executorch] Use temp allocator for allocating scratch memory #15728
• [Executorch] Introduce caching cpu memory allocator #15611
• Reduce allocation overhead in quantized sdpa #15610

Existing constructors dont compose well such that if you want data loader or data files constructor then you cannot get to override memory allocator.
Fix that.

Differential Revision: D86120037

[pytorch-bot]

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✅ You can merge normally! (1 Unrelated Failure)

As of commit 5d30170 with merge base a09a4b7 ():

BROKEN TRUNK - The following job failed but were present on the merge base:

👉 Rebase onto the `viable/strict` branch to avoid these failures

• pull / android / run-emulator (gh) (trunk failure)
  Timeout waiting for emulator to boot.

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