fix(native-filters): add support for versioned import/export

[villebro]

SUMMARY

This PR fixes native filter metadata in versioned import/export of dashboards by doing the following:

• export all datasets referenced in native filters, even those not referenced by charts in dashboard.
• replaces datasetId with datasetUuid in native filter targets to ensure that dataset reference is based on UUID, not numeric id.

Other bycatch fixes that were found while testing:

• Fix datatype of query_context in ImportV1ChartSchema, which should be String, not Dict (caused a marshmallow schema validation exception). Also make it accept None values and add JSON validation.
• datasource_type in dataset_info was set as view if the table was a virtual table, which caused an exception when importing virtual datasets. Since virtual datasets are in fact regular table datasources, we just reference the datasource_type of the imported dataset.

SCREENSHOT

Now native filter targets are referencing datasetUuid instead of datasetId:

TESTING INSTRUCTIONS

1. enable the "VERSIONED_EXPORT" feature flag
2. export a dashboard that had only one chart and two native filters, one referencing the same dataset as the chart and another not referenced by the chart
3. check that the native filter configurations in the dashboard metadata contain datasetUuid instead of datasetId references
4. delete the exported dashboard, chart and dataset only referenced by the native filter
5. import the exported bundle
6. make sure the imported dashboard works correctly, and that both datasets are imported correctly and native filter configurations are correct

ADDITIONAL INFORMATION

• Has associated issue: closes [Export Dashboard][Native Filter] Column selection is not saved in export file, and saving dataset id in export file doesn't seem to be a correct approach #15484 , closes The datasets used by native filters are not included in the dashboard export #15531
• Changes UI
• Includes DB Migration (follow approval process in SIP-59)
  • Migration is atomic, supports rollback & is backwards-compatible
  • Confirm DB migration upgrade and downgrade tested
  • Runtime estimates and downtime expectations provided
• Introduces new feature or API
• Removes existing feature or API

[villebro]

This caused a schema validation exception and needed to be changed to the string type

[villebro]

This also caused an import error, since virtual datasets are in fact regular tables (they just have the sql property set).

[codecov]

Codecov Report

Merging #16017 (6b0a652) into master (46188c1) will decrease coverage by 0.23%.
The diff coverage is 77.04%.

❗ Current head 6b0a652 differs from pull request most recent head 78d136e. Consider uploading reports for the commit 78d136e to get more accurate results

@@            Coverage Diff             @@
##           master   #16017      +/-   ##
==========================================
- Coverage   77.03%   76.80%   -0.24%     
==========================================
  Files         989      990       +1     
  Lines       52413    52491      +78     
  Branches     6634     6639       +5     
==========================================
- Hits        40378    40317      -61     
- Misses      11812    11950     +138     
- Partials      223      224       +1     

Flag	Coverage Δ
hive	?
mysql	81.57% <76.92%> (-0.06%)	⬇️
postgres	81.63% <76.92%> (-0.02%)	⬇️
presto	?
python	81.72% <78.84%> (-0.45%)	⬇️
sqlite	81.23% <78.84%> (-0.02%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
superset/charts/commands/export.py	94.28% <ø> (ø)
superset/commands/importers/v1/examples.py	38.02% <0.00%> (ø)
superset/security/manager.py	91.90% <ø> (ø)
superset/dashboards/commands/export.py	83.09% <33.33%> (-7.23%)	⬇️
superset/dashboards/commands/importers/v1/utils.py	80.59% <41.17%> (-13.53%)	⬇️
...erset-frontend/src/datasource/DatasourceEditor.jsx	74.15% <66.66%> (-0.85%)	⬇️
superset/connectors/sqla/utils.py	91.66% <91.66%> (ø)
superset/views/datasource.py	90.12% <95.00%> (+1.59%)	⬆️
superset/charts/schemas.py	100.00% <100.00%> (ø)
superset/connectors/sqla/models.py	88.00% <100.00%> (-1.84%)	⬇️
... and 11 more

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[zhaoyongjie]

Tested that all the new created dashboard are working fine.(both importing and exporting)