Share binary size threshold

[keshavb96]

When running JAX in a distributed system with multiple processes, only allow sharing of compiled modules when the cumulative size of constants in the pre-compiled graph is less than a threshold

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[nouiz]

@hawkinsp Can you take a look?

[keshavb96]

Done! Let me know if there are anymore issues.

[hawkinsp]

Please fix the presubmit errors (and sync up again, I guess)...