[cmake] final CPM fixes (#267)

- remove vcpkg references in docs
- move externals around
- fix non-cpm stuff
- remove redundant simpleini call/dir

Signed-off-by: crueter <[email protected]>

Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/267
Reviewed-by: Maufeat <[email protected]>

.ci/linux/build.sh

@@ -96,7 +96,6 @@ cmake .. -G Ninja \
     -DUSE_DISCORD_PRESENCE=ON \
     -DCMAKE_CXX_FLAGS="$ARCH_FLAGS" \
     -DCMAKE_C_FLAGS="$ARCH_FLAGS" \
-    -DYUZU_USE_BUNDLED_VCPKG=OFF \
     -DYUZU_USE_BUNDLED_QT=OFF \
     -DYUZU_USE_BUNDLED_SDL2=OFF \
     -DYUZU_USE_EXTERNAL_SDL2=ON \