feat(ingest/superset): add datasets ingestion

[Serge-B2]

Checklist

• The PR conforms to DataHub's Contributing Guideline (particularly Commit Message Format)
• Links to related issues (if applicable)
• Tests for the changes have been added/updated (if applicable)
• Docs related to the changes have been added/updated (if applicable). If a new feature has been added a Usage Guide has been added for the same.
• For any breaking change/potential downtime/deprecation/big changes an entry has been made in Updating DataHub

This PR introduces support for the Datasets entity in the Superset data ingestion plugin, enhancing its integration capabilities with DataHub.

[Serge-B2]

@hsheth2 Could you please review this.

[hsheth2]

Some higher level questions before I dive into the actual code

• Superset "datasets" are basically a view over data warehouse tables, right? For the most part, they have the same columns, plus some additional ones if using the "superset semantic layer"
• In this PR, the goal should be to draw warehouse <- superset dataset <- superset chart lineage, right? I suspect that ingesting only metadata about superset datasets, without lineage up to the warehouse, will make things confusing

[Serge-B2]

Some higher level questions before I dive into the actual code

• Superset "datasets" are basically a view over data warehouse tables, right? For the most part, they have the same columns, plus some additional ones if using the "superset semantic layer"
• In this PR, the goal should be to draw warehouse <- superset dataset <- superset chart lineage, right? I suspect that ingesting only metadata about superset datasets, without lineage up to the warehouse, will make things confusing

Yes, you are right, this PR is aimed towards ingesting Superset datasets which are views over warehouse tables. These datasets are of interest because they allow users to interact with the data and leverage some capabilities of the Superset layer in a user-friendly way. So we decided it would be helpful to introduce these into Datahub so we could have a more detailed view of Superset lineage. It is especially useful for the period when all or some of the sources that are used in Superset are unavailable for ingesting to Datahub due to different reasons. For example, we could not currently ingest sources that use sql_alchemy in its plugins because the proxy that we use for access doesn't allow for it. One of such sources is Clickhouse.

I also introduced "use_superset_platfrom" parameter to assign Superset platform to new datasets. Superset assigns the platform of the source to its datasets by default which indeed could be confusing and we are able to deal with it in this PR by changing platform to Superset.

One more thing to consider is that I make a distinction between datasets that are based on tables and on views, these datasets receive "virtual" tag.

[Serge-B2]

@hsheth2 could you please review this, I believe this PR will bring value to those who mainly use metadata from Superset