multiprocess: Add new bitcoin-gui, bitcoin-qt, bitcoin-wallet init implementations

Add separate init implementations instead of sharing existing bitcoind
and bitcoin-node ones, so they can start to be differentiated in
upcoming commits with node and wallet code no longer linked into the
bitcoin-gui binary and wallet code no longer linked into the
bitcoin-node binary.

build_msvc/bitcoin-qt/bitcoin-qt.vcxproj

@@ -9,7 +9,7 @@
   </PropertyGroup>
   <ItemGroup>
     <ClCompile Include="..\..\src\qt\main.cpp" />
-    <ClCompile Include="..\..\src\init\bitcoind.cpp" />
+    <ClCompile Include="..\..\src\init\bitcoin-qt.cpp" />
     <ResourceCompile Include="..\..\src\qt\res\bitcoin-qt-res.rc" />
   </ItemGroup>
   <ItemGroup>

build_msvc/bitcoin-wallet/bitcoin-wallet.vcxproj

@@ -10,6 +10,9 @@
   </PropertyGroup>
   <ItemGroup>
     <ClCompile Include="..\..\src\bitcoin-wallet.cpp" />
+    <ClCompile Include="..\..\src\init\bitcoin-wallet.cpp">
+      <ObjectFileName>$(IntDir)init_bitcoin-wallet.obj</ObjectFileName>
+    </ClCompile>
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\libbitcoinconsensus\libbitcoinconsensus.vcxproj">

build_msvc/test_bitcoin-qt/test_bitcoin-qt.vcxproj

@@ -8,7 +8,7 @@
     <OutDir>$(SolutionDir)$(Platform)\$(Configuration)\</OutDir>
   </PropertyGroup>
   <ItemGroup>
-    <ClCompile Include="..\..\src\init\bitcoind.cpp" />
+    <ClCompile Include="..\..\src\init\bitcoin-qt.cpp" />
     <ClCompile Include="..\..\src\test\util\setup_common.cpp" />
     <ClCompile Include="..\..\src\qt\test\addressbooktests.cpp" />
     <ClCompile Include="..\..\src\qt\test\apptests.cpp" />