Update Windows build documentation

[pajlada]

Pull request checklist:

• CHANGELOG.md was updated, if applicable

Description

This moves CMake to be our top supported build method, with Qt creator
being lower priority now.

This was tested on a real Windows 10 machine from scratch.

Would appreciate some proof-reading, especially of the CMake part (it should be pretty short)

[ScrubN]

BUILDING_ON_WINDOWS_WITH_VCPKG.md can also be updated.

• Just last night I installed everything I did not already have (so not git or Desktop C++) and from start (before vcpkg) to having chatterino2.exe compiled I think it took about 44GB of storage space: 41GB for vcpkg/downloads, vcpkg/buildtrees, vcpkg/packages and 3GB for chatterino2/build.

• Pwsh interprets the ; in 5.3 as denoting a new command, meaning the system environment variable editor (SystemPropertiesAdvanced.exe) must be used instead.

• I personally think set VCPKG_ROOT=C:\path\to\vcpkg\ should be switched to set VCPKG_ROOT=<path to vcpkg> to match with cmake --build . --parallel <threads> --config Release right below

• A shell restart is mandatory between Prerequisites and Building if vcpkg was just installed.