Adding onetrace_enabled

Example of usage:

```
(dev_dpctl) opavlyk@opavlyk-mobl:~/repos/dpctl$ ~/pti-gpu/tools/onetrace/build/onetrace --conditional-collection -v -t --demangle ipython
Device Timeline: start time (CLOCK_MONOTONIC_RAW) [ns] = 207284739877222
Device Timeline: start time (CLOCK_MONOTONIC) [ns] = 207284790110055
Device Timeline: start time (CLOCK_REALTIME) [ns] = 1662686020459161393
Python 3.9.12 (main, Jun  1 2022, 11:38:51)
Type 'copyright', 'credits' or 'license' for more information
IPython 8.4.0 -- An enhanced Interactive Python. Type '?' for help.

In [1]: import dpctl.tensor as dpt, dpctl, numpy as np
Device Timeline: start time (CLOCK_MONOTONIC_RAW) [ns] = 207294358012969
Device Timeline: start time (CLOCK_MONOTONIC) [ns] = 207294408245381
Device Timeline: start time (CLOCK_REALTIME) [ns] = 1662686030077296715

Device Timeline: start time (CLOCK_MONOTONIC_RAW) [ns] = 207294447416361
Device Timeline: start time (CLOCK_MONOTONIC) [ns] = 207294497648642
Device Timeline: start time (CLOCK_REALTIME) [ns] = 1662686030166699977

Device Timeline: start time (CLOCK_MONOTONIC_RAW) [ns] = 207294522074685
Device Timeline: start time (CLOCK_MONOTONIC) [ns] = 207294572308151
Device Timeline: start time (CLOCK_REALTIME) [ns] = 1662686030241359487

Device Timeline: start time (CLOCK_MONOTONIC_RAW) [ns] = 207294602756763
Device Timeline: start time (CLOCK_MONOTONIC) [ns] = 207294652988740
Device Timeline: start time (CLOCK_REALTIME) [ns] = 1662686030322040075

In [2]: from dpctl.utils import onetrace_enabled

In [3]: with onetrace_enabled():
   ...:     dpt.linspace(0, 1, num=1000, dtype='f4')
   ...:     dpt.arange(0, 20, dtype='i4')
   ...:
Device Timeline (queue: 0x56315e00e720): linear_sequence_affine_kernel<float, float>[SIMD32 {5; 1; 1} {200; 1; 1}]<1.1> [ns] = 49099144803 (append) 49099446053 (submit) 49101192928 (start) 49101202303 (end)
Device Timeline (queue: 0x56315e00e720): linear_sequence_step_kernel<int>[SIMD32 {1; 1; 1} {20; 1; 1}]<2.1> [ns] = 49154332484 (append) 49154668024 (submit) 49155196149 (start) 49155213440 (end)

In [4]: quit

Segmentation fault
```

The segmenation fault at the exit is a known issue with ZE-tracer module.

Author: oleksandr-pavlyk

dpctl/utils/__init__.py

@@ -23,9 +23,11 @@
     get_execution_queue,
     validate_usm_type,
 )
+from ._onetrace_context import onetrace_enabled
 
 __all__ = [
     "get_execution_queue",
     "get_coerced_usm_type",
     "validate_usm_type",
+    "onetrace_enabled",
 ]

dpctl/utils/_onetrace_context.py

@@ -0,0 +1,53 @@
+#                      Data Parallel Control (dpctl)
+#
+# Copyright 2020-2022 Intel Corporation
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import os
+from contextlib import contextmanager
+
+
+@contextmanager
+def onetrace_enabled():
+    """ Enable `onetrace` collection for kernels executed in this context.
+
+    N.B.: Proper working of this utility assumes that Python interpreter
+    has been launched by `onetrace` tool from intel/pti-gpu project.
+
+        .. Example:: bash
+
+            $ onetrace --conditional-collection -v -t --demangle \
+                python script.py
+
+        .. Example:: bash
+
+            import dpctl.tensor as dpt
+            from dpctl.utils import onetrace_enabled
+
+            # onetrace output reporting on execution of the kernel
+            # should be seen, starting with "Device Timeline"
+            with onetrace_enabled():
+                dpt.arange(100, dtype='int16')
+
+    """
+    _env_var_name = "PTI_ENABLE_COLLECTION"
+    saved = os.getenv(_env_var_name, None)
+    try:
+        os.environ[_env_var_name] = "1"
+        yield
+    finally:
+        if saved is None:
+            del os.environ[_env_var_name]
+        else:
+            os.environ[_env_var_name] = saved