* Fix null handle
- use .handle=0, not .handle=numeric_limits<>::max()
* Update lib.common.hasher
* Fix ROCPROFILER_CONTEXT_NONE
* Use context operator==
* Update CHANGELOG
* Updated null handle for scratch memory and changed allocation test so that free ops account for null agent
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Co-authored-by: Ian Trowbridge <Ian.Trowbridge@amd.com>