Remove use of uiInterface.LoadWallet in wallet code

This also changes the uiInterface.LoadWallet signal argument type from
shared_ptr<CWallet> to unique_ptr<interfaces::Wallet> because CWallet is an
internal wallet class that shouldn't be used in non-wallet code (and also can't
be passed across process boundaries).

This commit does not change behavior.

src/Makefile.bench.include

@@ -37,8 +37,6 @@ nodist_bench_bench_bitcoin_SOURCES = $(GENERATED_BENCH_FILES)
 bench_bench_bitcoin_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES) $(EVENT_CLFAGS) $(EVENT_PTHREADS_CFLAGS) -I$(builddir)/bench/
 bench_bench_bitcoin_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
 bench_bench_bitcoin_LDADD = \
-  $(LIBBITCOIN_WALLET) \
-  $(LIBBITCOIN_SERVER) \
   $(LIBBITCOIN_WALLET) \
   $(LIBBITCOIN_SERVER) \
   $(LIBBITCOIN_COMMON) \