feat(group.ts): add static method `toInput` for Group instance #3463

Job	Run time
Build-And-Test-Server (Simple integration tests)	17m 31s
Build-And-Test-Web	4m 58s
Build-And-Test-Server (DEX integration tests)	13m 6s
Build-And-Test-Server (DEX integration test with proofs)	12m 49s
Build-And-Test-Server (Voting integration tests)	5m 36s
Build-And-Test-Server (Unit tests)	39m 56s
Build-And-Test-Server (Verification Key Regression Check)	11m 35s
Build-And-Test-Server (CommonJS test)	2m 29s
Release-mina-signer-on-NPM	1m 49s
Release-on-NPM	1m 39s
	1h 51m 28s

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