fix(explore): Re-enable Explore re-render on Save As

[codyml]

SUMMARY

The combination of #20498 and #20645 caused a regression in Explore logic such that when a chart is saved as a new chart, the chart wouldn't render once the modal was closed without clicking the "Update Chart" button. This broke a Cypress test, explore/link.test.ts that's currently failing on master, but which wasn't picked up by CI before merge because CI on #20645 was run before #20498 had been merged and the two PRs didn't have any conflicts that would prompt GH to require a rebase. This PR reverts a little bit of #20645, making the HYDRATE_EXPLORE Redux action once again update the datasources store key in the same step instead of in a different step. I don't really understand why this change fixes the issue, but it seems like the Explore components only refresh as expected if datasources is updated as part of the HYDRATE_EXPLORE action.

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

Before:

Screen.Recording.2022-07-13.at.7.25.46.PM.mov

After:

Screen.Recording.2022-07-13.at.7.23.58.PM.mov

TESTING INSTRUCTIONS

• Check that saving a chart as a new chart causes the chart to render.
• Check that Cypress tests are now passing.

ADDITIONAL INFORMATION

• Has associated issue:
• 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

[michael-s-molina]

We can't have Explore actions inside the datasource module because datasources are a shared resource. Let's sync on this.

[codecov]

Codecov Report

Merging #20704 (95dc1d7) into master (6b0bb80) will decrease coverage by 0.00%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##           master   #20704      +/-   ##
==========================================
- Coverage   66.83%   66.83%   -0.01%     
==========================================
  Files        1750     1750              
  Lines       65894    65895       +1     
  Branches     7017     7018       +1     
==========================================
- Hits        44041    44039       -2     
- Misses      20067    20069       +2     
- Partials     1786     1787       +1     

Flag	Coverage Δ
javascript	51.93% <0.00%> (-0.01%)	⬇️

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

Impacted Files	Coverage Δ
superset-frontend/src/datasource/reducer.ts	11.11% <0.00%> (-3.18%)	⬇️
...set-frontend/src/explore/actions/hydrateExplore.ts	60.00% <ø> (-1.54%)	⬇️
superset-frontend/src/datasource/actions.ts	0.00% <0.00%> (-33.34%)	⬇️

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[michael-s-molina]

Approving this as a hot-fix. We should remove Explore specific state from the datasources reducer.

[michael-s-molina]

We can't remove initDatasources. Can you restore that line and check if the bug continues to be fixed?

[codyml]

Closing in favor of #20796.