fix: Allow Smithy enum & intEnum to bind to event headers #5071

Job	Run time
linux (ubuntu-24.04-arm, jammy, 5.9)	7m 25s
linux (ubuntu-24.04, jammy, 5.9)	8m 44s
apple (macos-26, Xcode_26.0, platform=tvOS Simulator,OS=26.0,name=Apple TV 4K (3rd generation) (a...	12m 35s
apple (macos-14, Xcode_15.2, platform=tvOS Simulator,OS=17.2,name=Apple TV 4K (3rd generation) (a...	8m 39s
apple (macos-14, Xcode_15.2, platform=macOS)	10m 4s
linux (ubuntu-24.04, jammy, 6.2)	9m 10s
linux (ubuntu-24.04-arm, jammy, 6.2)	7m 26s
apple (macos-14, Xcode_15.2, platform=visionOS Simulator,OS=1.0,name=Apple Vision Pro)	10m 44s
apple (macos-26, Xcode_26.0, platform=iOS Simulator,OS=26.0,name=iPhone 17)	12m 50s
apple (macos-26, Xcode_26.0, platform=visionOS Simulator,OS=26.0,name=Apple Vision Pro)	13m 36s
apple (macos-14, Xcode_15.2, platform=iOS Simulator,OS=17.2,name=iPhone 15)	12m 2s
apple (macos-26, Xcode_26.0, platform=macOS)	10m 23s
	2h 3m 38s

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