Apparently conan's prebuilt package ships without a runtime check for
AVX, crashing yuzu on devices without it.
Reverting this to externals seems to fix it. This wasn't tested on a CPU
without AVX, but it was tested with the following change on Windows:
bcdedit /set xsavedisable 1
master crashes inside opus code with an illegal instruction, this commit
doesn't.
* Remove git submodules that will be loaded through conan
* Move custom Find modules to their own folder
* Use conan for downloading missing external dependencies
* CI: Change the yuzu source folder user to the user that the containers run on
* Attempt to remove dirty mingw build hack
* Install conan on the msvc build
* Only set release build type when using not using multi config generator
* Re-add qt bundled to workaround an issue with conan qt not downloading prebuilt binaries
* Add workaround for submodules that use legacy CMAKE variables
* Re-add USE_BUNDLED_QT on the msvc build bot
