Added derivative and Hessian for Easom test function #993

Job	Run time
tests-argmin-observer-slog	18s
tests-argmin-serde1-feature	1m 36s
tests-argmin	3m 24s
tests-argmin-checkpointing-file	11s
tests-argmin-math	4m 30s
tests-argmin-observer-paramwriter	13s
tests-argmin-observer-spectator	51s
tests-argmin-testfunctions	22s
cargo-deny (advisories)	28s
clippy	3m 5s
cargo-deny (bans licenses sources)	32s
docs-build	13s
rustfmt	17s
wasm-build	24s
	16m 24s

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