Implement `onPageLoad` for playwright #1789

Job	Run time
Build for native target (macos-15, Xcode_16.4)	48s
Build and Test (ubuntu-22.04, https://download.swift.org/development/ubuntu2204/swift-DEVELOPMENT...	6m 9s
Build and Test (ubuntu-22.04, https://download.swift.org/swift-6.1-release/ubuntu2204/swift-6.1-R...	6m 4s
Build and Test (ubuntu-22.04, https://download.swift.org/swift-6.0.2-release/ubuntu2204/swift-6.0...	4m 49s
Build and Test (ubuntu-22.04, https://download.swift.org/development/ubuntu2204/swift-DEVELOPMENT...	6m 30s
format	32s
check-bridgejs-generated	6m 12s
build-examples	11m 13s
deploy-examples	0s
	42m 17s

Provide feedback