feat(frost-core): simplify trait bounds, don't use the allocator in some places #1494

Job	Run time
actionlint	6s
build with MSRV (1.66.1)	2m 44s
build with default features	29s
Clippy	36s
Check Rust doc	36s
build with no_std (ristretto255)	26s
Rustfmt	9s
build with no_std (ed25519)	26s
Check if automatically generated code is up to date	28s
test on beta	2m 21s
build with no_std (p256)	27s
build with no_std (secp256k1)	28s
build with no_std (secp256k1-tr)	28s
build with no_std (rerandomized)	25s
	10m 9s

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