feat: implementing answerProspectiveValidationDataRequest

[KaioApeles]

Changes

Implemented function answerProspectiveValidationDataRequest in prospective-parachains.go file

Tests

go test -timeout 30s -run ^TestAnswerProspectiveValidationDataRequest$ github.com/ChainSafe/gossamer/dot/parachain/prospective-parachains

Issues

Closes #4313

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