Changes for executor actor recovery using ray's fault tolerance.

[KiranP-d11]

Pull request for the bug described in the issue #364.

This is the fix for ray executors not recovering from OOM and other failures.
The issue is because of the race condition:

 - Executor E1 dies lets say because of OOM
 - We try to kill it by firing stop call on E1 actor
 - Since the actor is not available, the stop task fails for E1
 - In the mean while, ray brings up the lost executor E1
 - The failed task (stop task) gets retried as there are task retries configured.
 - The stop task gets fired on the new executor which got recovered
 - The Recovered executor exits with status as user intended exit.

[kira-lin]

Hi @KiranP-d11
This is great. Thanks for your work!
I have already merged the pr which fixes raydp-submit, can you please merge the main branch and try CI again?
The file changes LGTM to me

[KiranP-d11]

@kira-lin Merged the master branch and CI checks are passing.