Add opt-in tracing hooks for JS bridge #2008

Job	Run time
check-bridgejs-generated	2m 47s
Build and Test (ubuntu-24.04, https://download.swift.org/development/ubuntu2404/swift-DEVELOPMENT...	51s
Build and Test (ubuntu-22.04, https://download.swift.org/development/ubuntu2204/swift-DEVELOPMENT...	48s
Build and Test (ubuntu-22.04, https://download.swift.org/swift-6.1-release/ubuntu2204/swift-6.1-R...	44s
format	31s
Build for native target (macos-15, Xcode_16.4)	2m 13s
build-examples	5m 27s
Build and Test (ubuntu-24.04, https://download.swift.org/swift-6.3-branch/ubuntu2404/swift-6.3-DE...	46s
deploy-examples	1s
	14m 8s

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