fix: Move chart samples to explore resource endpoint

[hughhhh]

SUMMARY

Since samples endpoint need to support not only datasets but also other datasource types. I decided moving it to the explore view.

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

TESTING INSTRUCTIONS

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

[codecov-commenter]

Codecov Report

Merging #233 (56fcdc9) into chart-power-query (fa85488) will decrease coverage by 0.02%.
The diff coverage is 52.94%.

@@                  Coverage Diff                  @@
##           chart-power-query     #233      +/-   ##
=====================================================
- Coverage              66.31%   66.29%   -0.03%     
=====================================================
  Files                   1757     1758       +1     
  Lines                  66577    66654      +77     
  Branches                7066     7066              
=====================================================
+ Hits                   44148    44185      +37     
- Misses                 20629    20669      +40     
  Partials                1800     1800              

Flag	Coverage Δ
hive	53.21% <51.21%> (-0.02%)	⬇️
javascript	51.92% <100.00%> (ø)
mysql	81.04% <51.21%> (-0.08%)	⬇️
postgres	81.11% <51.21%> (-0.08%)	⬇️
presto	53.07% <51.21%> (-0.02%)	⬇️
python	81.54% <51.21%> (-0.08%)	⬇️
sqlite	80.90% <51.21%> (-0.08%)	⬇️
unit	50.16% <45.12%> (-0.02%)	⬇️

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

Impacted Files	Coverage Δ
superset/explore/commands/samples.py	42.22% <42.22%> (ø)
superset/explore/api.py	71.21% <48.00%> (-15.16%)	⬇️
superset/common/query_actions.py	92.30% <83.33%> (-0.85%)	⬇️
...erset-frontend/src/components/Chart/chartAction.js	55.92% <100.00%> (ø)
...mponents/DataTablesPane/components/SamplesPane.tsx	97.67% <100.00%> (ø)
superset/explore/exceptions.py	100.00% <100.00%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update fa85488...56fcdc9. Read the comment docs.