refacto handlers and services

index.ts

src/handlers/association/associationHandlers.ts

src/handlers/balance/balanceHandlers.ts

src/handlers/handlers.ts

src/handlers/proposal/proposalHandlers.ts

src/handlers/roleHandlers.ts

src/handlers/token/tokenHandlers.ts

src/services/association.service.ts

src/services/contract.service.ts

src/services/token.service.ts

src/utils/getRole.ts

test/handlers/association/associationHandlers.spec.ts

test/handlers/balance/balanceHandlers.spec.ts

test/handlers/proposal/proposalHandlers.spec.ts

test/handlers/roleHandlers.spec.ts

test/handlers/token/tokenHandlers.spec.ts