BridgeJS: Optimize string encoding for JS-to-Swift crossings #2651

Job	Run time
prettier	9s
Test BridgeJS against Swift versions (swift:6.2, 602.0.0)	3m 13s
Build and Test (ubuntu-22.04, https://download.swift.org/swift-6.1-release/ubuntu2204/swift-6.1-R...	14m 12s
Build for native target (macos-15, Xcode_16.4)	2m 46s
Build and Test (ubuntu-22.04, https://download.swift.org/development/ubuntu2204/swift-DEVELOPMENT...	14m 30s
Build and Test (ubuntu-24.04, https://download.swift.org/swift-6.3-branch/ubuntu2404/swift-6.3-DE...	14m 31s
Test BridgeJS against Swift versions (swift:6.1.2, 601.0.0)	2m 51s
check-bridgejs-generated	2m 47s
Test BridgeJS against Swift versions (swift:6.3, 603.0.0)	3m 6s
format	35s
build-examples	21m 1s
Build and Test (ubuntu-24.04, https://download.swift.org/development/ubuntu2404/swift-DEVELOPMENT...	14m 29s
deploy-examples	-1s
	1h 34m 9s

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