Adding Azure Data Studio migration dialog

[Benjin]

Description

Adding a dialog to import connections and connection groups from Azure Data Studio.

Behavior:

• Automatically detects ADS settings files in default locations, but users can browse for any settings file
• Users can select individual connection groups and connections for import
• Already-imported connections and groups are detected and can be skipped or re-imported (matched via ID)
• Users can enter passwords for SQL Auth connections, and select (and sign into) Entra accounts for AzureMFA auth connections

Fixes #18661

Code Changes Checklist

• New or updated unit tests added
• All existing tests pass (npm run test)
• Code follows contributing guidelines
• Telemetry/logging updated if relevant
• No regressions or UX breakage

Reviewers: Please read our reviewer guidelines

[github-actions]

PR Changes

Category	Target Branch	PR Branch	Difference
vscode-mssql VSIX	5289 KB	5300 KB	⚪ 11 KB ( 0% )
sql-database-projects VSIX	5668 KB	5668 KB	⚪ 0 KB ( 0% )
data-workspace VSIX	null KB	542 KB	⚪ 542 KB ( 0% )

[codecov-commenter]

Codecov Report

❌ Patch coverage is 67.08861% with 130 lines in your changes missing coverage. Please review.
✅ Project coverage is 66.34%. Comparing base (24d2641) to head (c8ef9f9).
⚠️ Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
...llers/azureDataStudioMigrationWebviewController.ts	65.74%	124 Missing ⚠️
extensions/mssql/src/controllers/mainController.ts	20.00%	4 Missing ⚠️
extensions/mssql/src/constants/locConstants.ts	88.88%	2 Missing ⚠️

❌ Your patch status has failed because the patch coverage (67.08%) is below the target coverage (70.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@           Coverage Diff            @@
##             main   #20869    +/-   ##
========================================
  Coverage   66.33%   66.34%            
========================================
  Files         210      212     +2     
  Lines       20235    20630   +395     
  Branches     2634     2704    +70     
========================================
+ Hits        13423    13687   +264     
- Misses       6716     6846   +130     
- Partials       96       97     +1     

Files with missing lines	Coverage Δ
extensions/mssql/src/constants/constants.ts	100.00% <100.00%> (ø)
...l/src/sharedInterfaces/azureDataStudioMigration.ts	100.00% <100.00%> (ø)
extensions/mssql/src/sharedInterfaces/telemetry.ts	100.00% <100.00%> (ø)
extensions/mssql/src/constants/locConstants.ts	86.93% <88.88%> (+0.03%)	⬆️
extensions/mssql/src/controllers/mainController.ts	17.28% <20.00%> (+0.01%)	⬆️
...llers/azureDataStudioMigrationWebviewController.ts	65.74% <65.74%> (ø)

... and 1 file with indirect coverage changes

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