Add webview testing infrastructure and pnpm catalog #1885

Job	Run time
Unit Test (Electron latest)	1m 4s
Integration Test (VS Code 1.95.0)	1m 14s
Lint	50s
Unit Test (Electron 32)	1m 5s
Integration Test (VS Code stable)	1m 14s
Package	-1s
	5m 26s

Provide feedback