feat!: new v1beta2 asset models

[StewartJingga]

Package to be fixed:

• [x] agent
• [x] bigquery
• [x] bigtable
• [x] cassandra
• [x] clickhouse
• [x] couchdb
• [x] csv
• [x] elastic
• [x] gcs
• [x] github
• [x] grafana
• [x] kafka
• [x] mariadb
• [x] metabase
• [x] mongodb
• [x] mssql
• [x] mysql
• [x] optimus
• [x] oracle
• [x] postgres
• [x] presto
• [x] redash
• [x] redshift
• [x] shield
• [x] snowflake
• [x] superset
• [x] tableau
• [x] processors
• [x] file sink
• [x] http sink
• [x] stencil sink
• [x] mocks - plugins.go
• [x] utils - custom_properties.go

[GrayFlash]

Picking up on reviewing this PR, have good context, so will review the changes. Mas @StewartJingga you can also check once, on the changes I have made. Let me know if I'm missing something.

[GrayFlash]

Rest of the changes in plugins LGTM!!

[bsushmith]

@StewartJingga Can you link the corresponding issue with details to this PR.

Also, would this change break the recipe contracts by any chance?

If, from a usage perspective, there is a breaking change - can you also add details about what is breaking and what needs to be done to accommodate these in the corresponding issue.