add trait `ScalarComposite` #1182

Job	Run time
Lint	6m 18s
Compiletest (ubuntu-24.04)	7m 31s
Compiletest (macOS-latest)	9m 39s
Android (ubuntu-24.04, aarch64-linux-android)	8m 22s
cargo-deny	1m 10s
Compiletest (windows-2022)	16m 22s
Test (ubuntu-24.04)	10m 54s
Test (windows-2022)	17m 36s
Test (macOS-latest)	10m 32s
Difftest (windows-2022)	24m 7s
Difftest (macOS-latest)	21m 59s
Difftest (ubuntu-24.04)	14m 25s
test_success	2s
	2h 28m 57s

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