Enable FP16 for Lexan #4550

Job	Run time
build-and-test / bazel-linux-x86_64-gcc-9	5m 41s
build-and-test / bazel-linux-x86_64-clang-18	6m 52s
build-and-test / bazel-linux-aarch64-clang18	9m 59s
build-and-test / bazel-linux-aarch64-gcc13	8m 25s
build-and-test / cmake-android (arm64)	4m 30s
build-and-test / cmake-ios-arm64	2m 32s
build-and-test / cmake-ios-x86_64	4m 9s
build-and-test / cmake-android (armv7)	4m 59s
build-and-test / cmake-linux-aarch64	2m 0s
build-and-test / cmake-android (x86)	4m 19s
build-and-test / cmake-linux-armhf	3m 14s
build-and-test / cmake-linux-riscv64	7m 20s
build-and-test / cmake-linux-riscv64-rvv	6m 49s
build-and-test / cmake-linux-x86_64	5m 2s
build-and-test / cmake-macos-arm64	1m 14s
build-and-test / cmake-windows-arm64	3m 51s
build-and-test / cmake-windows-x64	2m 51s
build-and-test / cmake-windows-x86	3m 15s
	1h 27m 2s

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