Added timeout to w.clusters.ensure_cluster_running() (#227)

## Changes

This picks up where #118 left off.

<!-- Summary of your changes that are easy to understand -->

## Tests
<!-- 
How is this tested? Please see the checklist below and also describe any
other relevant tests
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- [x] `make test` run locally
- [x] `make fmt` applied
- [x] relevant integration tests applied

---------

Co-authored-by: Serge Smertin <259697+nfx@users.noreply.github.com>

databricks/sdk/mixins/compute.py

@@ -1,9 +1,15 @@
+import datetime
+import logging
 import re
+import time
 from dataclasses import dataclass
 from typing import Optional
 
+from databricks.sdk.errors import OperationFailed
 from databricks.sdk.service import compute
 
+_LOG = logging.getLogger('databricks.sdk')
+
 
 @dataclass
 class SemVer:
@@ -203,16 +209,28 @@ def select_node_type(self,
             return nt.node_type_id
         raise ValueError("cannot determine smallest node type")
 
-    def ensure_cluster_is_running(self, cluster_id: str):
+    def ensure_cluster_is_running(self, cluster_id: str) -> None:
         """Ensures that given cluster is running, regardless of the current state"""
-        state = compute.State
-        info = self.get(cluster_id)
-        if info.state == state.TERMINATED:
-            self.start(cluster_id).result()
-        elif info.state == state.TERMINATING:
-            self.wait_get_cluster_terminated(cluster_id)
-            self.start(cluster_id).result()
-        elif info.state in (state.PENDING, state.RESIZING, state.RESTARTING):
-            self.wait_get_cluster_running(cluster_id)
-        elif info.state in (state.ERROR, state.UNKNOWN):
-            raise RuntimeError(f'Cluster {info.cluster_name} is {info.state}: {info.state_message}')
+        timeout = datetime.timedelta(minutes=20)
+        deadline = time.time() + timeout.total_seconds()
+        while time.time() < deadline:
+            try:
+                state = compute.State
+                info = self.get(cluster_id)
+                if info.state == state.RUNNING:
+                    return
+                elif info.state == state.TERMINATED:
+                    self.start(cluster_id).result()
+                    return
+                elif info.state == state.TERMINATING:
+                    self.wait_get_cluster_terminated(cluster_id)
+                    self.start(cluster_id).result()
+                    return
+                elif info.state in (state.PENDING, state.RESIZING, state.RESTARTING):
+                    self.wait_get_cluster_running(cluster_id)
+                    return
+                elif info.state in (state.ERROR, state.UNKNOWN):
+                    raise RuntimeError(f'Cluster {info.cluster_name} is {info.state}: {info.state_message}')
+            except OperationFailed as e:
+                _LOG.debug('Operation failed, retrying', exc_info=e)
+        raise TimeoutError(f'timed out after {timeout}')