Move FillPSBT to be a member of CWallet

src/Makefile.am

@@ -241,7 +241,6 @@ BITCOIN_CORE_H = \
   wallet/fees.h \
   wallet/ismine.h \
   wallet/load.h \
-  wallet/psbtwallet.h \
   wallet/rpcwallet.h \
   wallet/scriptpubkeyman.h \
   wallet/wallet.h \
@@ -349,7 +348,6 @@ libbitcoin_wallet_a_SOURCES = \
   wallet/feebumper.cpp \
   wallet/fees.cpp \
   wallet/load.cpp \
-  wallet/psbtwallet.cpp \
   wallet/rpcdump.cpp \
   wallet/rpcwallet.cpp \
   wallet/scriptpubkeyman.cpp \