[CSL-124] Use `SafeSigner` in wallet methods
[CSL-124] Use `SafeSigner` in wallet methods

input-output-hk/cardano-sl,input-output-hk/cardano-sl,input-output-hk/cardano-sl,input-output-hk/pos-haskell-prototype,input-output-hk/pos-haskell-prototype,input-output-hk/pos-haskell-prototype,input-output-hk/cardano-sl