Based on #387
Add purview registry.

Keep sql registry code unchanged to avoid conflict.
Conform to Registy interfaces, provide same method and data format.

NOTICE that :
This PR does not totally eliminate the risk of concurrent conflict.
In old version, we update all entities like
purviewclient.upload_entities([entity_batch])
In this PR, several changes has been applied to shrink the time window for a concurrent race condition to happen:

1. For entity uploading, only one entity was filled into the batch. (This means, register 1 entity for 1 upload)
2. Check for entity existence before uploading by qualifeidName+typeName. If the matching entity exists, we will further check if these entities are identical, if not (an "update" operation), registry api will return HTTP409 Conflict.

Limitations:
By applying changes above to purview registry, the time window for a race condition to happen shrinks, but not eliminated.
A complete change needs discussion with Purview team about recommended way to secure MVCC.