vcpkg dependency builds for macOS

[LRFLEW]

It's been a while. Since my last PR to vcpkg was finally closed, I've been trying to get this working. This is using vcpkg a bit outside of the supported use case (macOS dynamic library builds are not officially supported), but it seems to be stable enough that it shouldn't be a huge issue. I got a number of the dependencies working, but some will require port updates in vcpkg to work correctly. Here's the current status of what I'm missing:

• duktape (depends on Use OS-included Python 2.7 on macOS microsoft/vcpkg#14662) (soft depends on [duktape] Add VERSION and SOVERSION properties CMake build microsoft/vcpkg#14666) (soft depends on [duktape] pyyaml installation fails on macOS (does not block port installing) microsoft/vcpkg#14741)
• speexdsp (depends on [speexdsp] Update CMake script for macOS/Linux microsoft/vcpkg#14758)
• openssl (depends on [openssl] Handle INSTALL_NAME_DIR and OSX_DEPLOYMENT_TARGET for macOS shared builds microsoft/vcpkg#14785)
• System zlib and bzip2 (depends on Fix instances of incorrect if(ENV{...}) usage and ENV{PKG_CONFIG_PATH} not being reset microsoft/vcpkg#14799)
• Remove brotli from build (depends on [freetype] Make zlib and brotli features microsoft/vcpkg#14917)

I haven't been following the changes in the project much recently, so I might be very likely missing something. I think I have everything based on the current dependencies release for macOS. With this change, it could also be an opportunity to add other dependencies that have been on a "wishlist", such as discord-rpc, so let me know if there's anything else you want me to look into for this.

[LRFLEW]

The most recent push has the script referring to my fork of vcpkg and using my branch where I have all my outstanding PR's merged in. With this, the PR should be testable while we wait for the upstream changes. I expect the release ZIPs to be the files in vcpkg/installed/x64-osx-openrct2/. It's a little bit more than necessary, but as long as symlinks are repsected when ZIPing, it shouldn't be too much.

[LRFLEW]

Ok, everything is merged up-stream in vcpkg except for one thing. Since that one PR seems to be held up by a larger refactor, I added a patch here that has the bug fix required for this to work. The patch can be removed once the upstream issue gets patched. This is ready to be reviewed now.

There is room to add more libraries to this build if there are any that should be added. I added discord-rpc, as there seems to a need for it based on OpenRCT2/OpenRCT2#13558. I also disabled the use of Brotli in freetype2, which can be re-enabled if support for WOFF2 fonts is desired. We could also consider using Brotli instead of Zlib for save compression when connecting to servers if we add it to the build.

Let me know if there are any other libraries you would want added to the build, and I can check if there are any upstream patches required to make the dylib-id and min macOS version work correctly.