Implement `onPageLoad` for playwright #1792

Job	Run time
Build for native target (macos-15, Xcode_16.4)	35s
format	36s
Build and Test (ubuntu-22.04, https://download.swift.org/swift-6.0.2-release/ubuntu2204/swift-6.0...	4m 51s
Build and Test (ubuntu-22.04, https://download.swift.org/development/ubuntu2204/swift-DEVELOPMENT...	5m 28s
Build and Test (ubuntu-22.04, https://download.swift.org/swift-6.1-release/ubuntu2204/swift-6.1-R...	5m 29s
Build and Test (ubuntu-22.04, https://download.swift.org/development/ubuntu2204/swift-DEVELOPMENT...	6m 27s
check-bridgejs-generated	5m 56s
build-examples	11m 25s
deploy-examples	-1s
	40m 46s

Provide feedback