Related work items: MSFT-32957145
Retrieved from https://microsoft.visualstudio.com os.2020 OS official/rs_wdx_dxp_windev bdb25dc99dcb2f1ee483dffe883d0178ea9d18dc
Visual Studio 2022 Preview recently released the v143 toolchain.
C4189 is now flagging several unused variables, which breaks our build.
## PR Checklist
* [x] I work here
* [x] Tests added/passed
## Validation Steps Performed
* CascadiaPackage builds ✔️
* All tests build ✔️
Many include statements use forward slashes, while others use backwards
slashes. This is inconsistent formatting. For this reason, I changed the
backward slashes to forward slashes since that is the standard.
* Removed using namespace directive from header files and put these in cpp files where they are used
* Fixed tabbing issues by replacing them with spaces.
Also regrouped the using directives.
* Update src/host/exemain.cpp
Co-Authored-By: Mike Griese <migrie@microsoft.com>
* Update src/interactivity/win32/find.cpp
Co-Authored-By: Mike Griese <migrie@microsoft.com>
