[0.19] Appveyor backports #17875

Changes are currently being backported to the 0.19 branch. However Appveyor is failing:

Build FAILED.
       "C:\projects\bitcoin\build_msvc\bitcoin.sln" (default target) (1) ->
       "C:\projects\bitcoin\build_msvc\testconsensus\testconsensus.vcxproj" (default target) (3) ->
       "C:\projects\bitcoin\build_msvc\libbitcoin_util\libbitcoin_util.vcxproj" (default target) (5) ->
       (ClCompile target) -> 
         c:\projects\bitcoin\src\util\system.h(36): fatal error C1083: Cannot open include file: 'boost/thread/condition_variable.hpp': No such file or directory [C:\projects\bitcoin\build_msvc\libbitcoin_util\libbitcoin_util.vcxproj]
       "C:\projects\bitcoin\build_msvc\bitcoin.sln" (default target) (1) ->
       "C:\projects\bitcoin\build_msvc\bitcoind\bitcoind.vcxproj" (default target) (4) ->
       "C:\projects\bitcoin\build_msvc\libbitcoin_common\libbitcoin_common.vcxproj" (default target) (6) ->
         c:\projects\bitcoin\src\util\system.h(36): fatal error C1083: Cannot open include file: 'boost/thread/condition_variable.hpp': No such file or directory [C:\projects\bitcoin\build_msvc\libbitcoin_common\libbitcoin_common.vcxproj]

My assumption is that vcpkg changes need to be backported, due to boost package splits.

I was able to get the branch building by clearing the appveyor cache and then:

wget [#17364](/bitcoin-bitcoin/17364/).diff
git apply 17364.diff
wget [#17416](/bitcoin-bitcoin/17416/).diff
git apply 17416.diff --exclude=build_msvc/README.md
wget [#17736](/bitcoin-bitcoin/17736/).diff
git apply 17736.diff

@sipsorcery great, thanks. I've cherry-pick those commits (didn't exclude the README in 17416) into #17858. Could you check / confirm there.