Implement PG connection verification

[adrinr]

Description

Implementing Postgres connection checks:

1. Typing datasources
2. Setting up connection tests in the interfaces
3. Implementing the connections tests for PG
4. Testing use cases

Addresses:

• https://linear.app/budibase/issue/BUDI-6932/verify-data-source-connection-during-configuration

[codecov-commenter]

Codecov Report

Merging #10545 (760d069) into feature/datasource-conns (12b06c8) will decrease coverage by 0.02%.
The diff coverage is 68.18%.

❗ Current head 760d069 differs from pull request most recent head d0a75a8. Consider uploading reports for the commit d0a75a8 to get more accurate results

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@@                     Coverage Diff                      @@
##           feature/datasource-conns   #10545      +/-   ##
============================================================
- Coverage                     69.89%   69.87%   -0.02%     
============================================================
  Files                           536      536              
  Lines                         19545    19552       +7     
  Branches                       3893     3893              
============================================================
+ Hits                          13661    13662       +1     
- Misses                         5449     5455       +6     
  Partials                        435      435              

Impacted Files	Coverage Δ
...r/src/migrations/functions/backfill/app/queries.ts	78.94% <ø> (-1.06%)	⬇️
packages/server/src/integrations/postgres.ts	55.14% <33.33%> (-2.55%)	⬇️
packages/server/src/integrations/index.ts	76.66% <88.88%> (+0.80%)	⬆️
packages/server/src/api/controllers/integration.ts	100.00% <100.00%> (ø)
...ages/server/src/sdk/app/datasources/datasources.ts	76.08% <100.00%> (ø)

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