Add `Add`/`Mul`/`SubAssign` bounds for `Integer` #1925

Job	Run time
careful	1m 22s
build-benchmarks	36s
build (1.83.0, thumbv7em-none-eabi)	47s
clippy	11s
build (1.83.0, wasm32-unknown-unknown)	39s
cross (aarch64-unknown-linux-gnu, stable)	2m 39s
build (stable, thumbv7em-none-eabi)	39s
cross (powerpc-unknown-linux-gnu, stable)	2m 54s
doc	21s
build (stable, wasm32-unknown-unknown)	48s
minimal-versions	38s
rustfmt	4s
miri (x86_64-unknown-linux-gnu)	3m 56s
test (i686-unknown-linux-gnu, 1.83.0, sudo apt update && sudo apt install gcc-multilib)	1m 48s
miri (s390x-unknown-linux-gnu)	4m 15s
test (i686-unknown-linux-gnu, stable, sudo apt update && sudo apt install gcc-multilib)	2m 2s
test (x86_64-unknown-linux-gnu, 1.83.0)	1m 33s
test (x86_64-unknown-linux-gnu, stable)	1m 29s
	26m 41s

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