xla

a9eb3459 - Implement `xm.rendezvous` with XLA collective communication for PJRT (#4181)

Implement `xm.rendezvous` with XLA collective communication for PJRT (#4181) * Implement pjrt.rendezvous with XLA collective ops. * Update tests. * Formatting * Handle some edge cases better * formatting * Add mesh service test to CI