Transferring active connection when opening a new SQL file

[Benjin]

Pull Request Template – vscode-mssql

Description

Fixes #19477

Automatically transfers connection from the active SQL file to a newly-opened SQL file.

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	Main Branch	PR Branch	Difference
Code Coverage	58.53%	58.50%	$${\color{lightgreen} -.03\% }$$
VSIX Size	15304 KB	15319 KB	$${\color{lightgreen} 15 KB \space (0\%) }$$
Webview Bundle Size	3692 KB	3688 KB	$${\color{lightgreen} -4 KB \space (0\%) }$$