fix: Ensure "Import Dashboard" menu item adheres to PVM

[john-bodley]

SUMMARY

This PR partially addresses Superset 3.0 task #36. The "Import Dashboard" menu item should adhere to the PVM and only render if the current user has the can import dashboards/Superset permission/view menu.

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

WITH PERMISSION

WITHOUT PERMISSION

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]

Codecov Report

Merging #24143 (c1af6e9) into master (2222073) will decrease coverage by 0.04%.
The diff coverage is 72.72%.

❗ Current head c1af6e9 differs from pull request most recent head 7271f86. Consider uploading reports for the commit 7271f86 to get more accurate results

@@            Coverage Diff             @@
##           master   #24143      +/-   ##
==========================================
- Coverage   68.30%   68.26%   -0.04%     
==========================================
  Files        1952     1952              
  Lines       75432    75350      -82     
  Branches     8191     8205      +14     
==========================================
- Hits        51521    51438      -83     
+ Misses      21807    21806       -1     
- Partials     2104     2106       +2     

Flag	Coverage Δ
hive	53.30% <23.20%> (+0.13%)	⬆️
mysql	78.94% <80.00%> (+<0.01%)	⬆️
postgres	79.02% <80.00%> (+<0.01%)	⬆️
presto	53.22% <24.00%> (+0.12%)	⬆️
python	82.82% <84.80%> (+0.01%)	⬆️
sqlite	77.55% <77.60%> (+<0.01%)	⬆️
unit	53.28% <24.80%> (+0.18%)	⬆️

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

Impacted Files	Coverage Δ
...set-ui-core/src/ui-overrides/ExtensionsRegistry.ts	100.00% <ø> (ø)
...et-frontend/src/components/TableSelector/index.tsx	81.08% <ø> (ø)
...end/src/features/databases/DatabaseModal/styles.ts	77.66% <ø> (ø)
superset-frontend/src/pages/DatabaseList/index.tsx	66.03% <0.00%> (ø)
superset/commands/importers/v1/assets.py	88.09% <0.00%> (+2.04%)	⬆️
superset/config.py	91.97% <ø> (-0.05%)	⬇️
superset/datasets/commands/importers/v1/utils.py	79.41% <0.00%> (+0.77%)	⬆️
superset/db_engine_specs/databricks.py	70.92% <0.00%> (+0.49%)	⬆️
superset/db_engine_specs/hive.py	87.54% <ø> (ø)
superset/db_engine_specs/snowflake.py	67.64% <0.00%> (+0.39%)	⬆️
... and 75 more

... and 1 file with indirect coverage changes

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