feat: add success message for database modal

[pkdotson]

SUMMARY

This pr adds success toast for the adding and updating a database.

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

After
https://user-images.githubusercontent.com/17326228/151241004-61ae73d2-af7f-4aff-9f12-85cf727a5101.mov

TESTING INSTRUCTIONS

Click on add database
add database of choosing and and hit connect.
After database closes should see toast message.

For updating database go to crudviews and update database info. After updating database should see toast

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 #18183 (17c5233) into master (2491b89) will increase coverage by 0.07%.
The diff coverage is 78.67%.

❗ Current head 17c5233 differs from pull request most recent head 41df6c7. Consider uploading reports for the commit 41df6c7 to get more accurate results

@@            Coverage Diff             @@
##           master   #18183      +/-   ##
==========================================
+ Coverage   65.97%   66.04%   +0.07%     
==========================================
  Files        1587     1591       +4     
  Lines       62176    62411     +235     
  Branches     6273     6283      +10     
==========================================
+ Hits        41020    41221     +201     
- Misses      19535    19569      +34     
  Partials     1621     1621              

Flag	Coverage Δ
javascript	50.85% <26.22%> (-0.04%)	⬇️

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

Impacted Files	Coverage Δ
.../superset-ui-core/src/connection/SupersetClient.ts	100.00% <ø> (ø)
...ackages/superset-ui-core/src/utils/featureFlags.ts	100.00% <ø> (ø)
superset-frontend/src/embedded/index.tsx	0.00% <0.00%> (ø)
superset-frontend/src/preamble.ts	0.00% <ø> (ø)
superset-frontend/src/setup/setupClient.ts	0.00% <0.00%> (ø)
superset-frontend/src/views/App.tsx	0.00% <0.00%> (ø)
...c/views/CRUD/data/database/DatabaseModal/index.tsx	32.46% <0.00%> (-0.22%)	⬇️
...perset-frontend/src/views/RootContextProviders.tsx	0.00% <0.00%> (ø)
superset/views/core.py	77.74% <0.00%> (+0.44%)	⬆️
superset/views/dashboard/views.py	65.16% <46.15%> (-4.07%)	⬇️
... and 19 more

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