[pjrt] Add an API to add user data to FFI context via PJRT_ExecuteContext
[pjrt] Add an API to add user data to FFI context via PJRT_ExecuteContext

FUTURE_COPYBARA_INTEGRATE_REVIEW=https://github.com/openxla/xla/pull/12633 from openxla:fix_multihost_runner_flag_parsing 71083c7d6dfdcaec1a5458b3f1cd04b11e13f8bd
