feat(chart-data-api): download multiple csvs as zip

[villebro]

SUMMARY

For charts that request more than one query, only the first result can be downloaded as CSV. This PR does the following:

• When downloading a CSV, return a CSV file if there is only one result (current behavior), but return all results bundled in a ZIP file if there are more than one results. Also add a unit test to ensure that requesting a multi-query QueryContext returns a zip with the expected contents
• If user tries to request CSV for a QueryContext with an empty queries property, return a 400. Also add a unit test for this case.
• Add assertion for the mimetype to the pre-existing single result CSV integration test
• Add assertion for the mimetype to the pre-existing JSON download integration test

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

TESTING INSTRUCTIONS

1. Create a Mixed Timeseries chart
2. Click the "Export to .CSV format" button
3. Verify that the downloaded ZIP file includes two CSVs with the correct contents

ADDITIONAL INFORMATION

• Has associated issue: closes exported csv file from Mixed Time-Series chart only contains one series #17960
• Required feature flags:
• 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

[codecov]

Codecov Report

Merging #18618 (f838c5f) into master (4e2bdd4) will increase coverage by 0.00%.
The diff coverage is 100.00%.

❗ Current head f838c5f differs from pull request most recent head 9246e81. Consider uploading reports for the commit 9246e81 to get more accurate results

@@           Coverage Diff           @@
##           master   #18618   +/-   ##
=======================================
  Coverage   66.30%   66.31%           
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  Files        1595     1595           
  Lines       62632    62647   +15     
  Branches     6309     6309           
=======================================
+ Hits        41529    41545   +16     
+ Misses      19453    19452    -1     
  Partials     1650     1650           

Flag	Coverage Δ
hive	52.14% <100.00%> (+0.07%)	⬆️
mysql	81.25% <100.00%> (+0.01%)	⬆️
postgres	81.30% <100.00%> (+0.01%)	⬆️
presto	51.99% <100.00%> (+0.07%)	⬆️
python	81.74% <100.00%> (+0.01%)	⬆️
sqlite	81.00% <100.00%> (+0.01%)	⬆️

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Impacted Files	Coverage Δ
superset/charts/data/api.py	89.80% <100.00%> (+0.99%)	⬆️
superset/utils/core.py	89.77% <100.00%> (+0.12%)	⬆️

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[geido]

/testenv up

[github-actions]

@geido Ephemeral environment spinning up at http://52.12.219.152:8080. Credentials are admin/admin. Please allow several minutes for bootstrapping and startup.

[geido]

LGTM!

[kgabryje]

When I use only 1 metric for a query, metric's name is not present in the csv

However, when I use more than 1 metric, I can see the metric names.

Is that intended behaviour?

[kgabryje]

Left a small comment, but since that behaviour wasn't introduced by this PR, LGTM!

[srinify]

Looks good, just tested! Approving :]

[github-actions]

Ephemeral environment shutdown and build artifacts deleted.