Engine artifacts build via docker should be runnable without `install`

Instead of just running `spring`/`spring.exe` executable from build output, the build scripts always runs `install` step and asks user to use output in `{builddir}/install/`.

This is:
- error prone
- install is fast, but it's still unnecessary delay

The minimal thing I see is that the paths in [specially generated](https://github.com/beyond-all-reason/RecoilEngine/blob/67736294de14eac8fb068dbda0f4dcbe20dfb306/cont/CMakeLists.txt#L42) `{builddir}/springsettings.cfg` map to locations inside of container, not on host:
```
SpringData = /build/out:/build/src/cont
FontFile = /build/src/cont/fonts/FreeSansBold.otf
SmallFontFile = /build/src/cont/fonts/FreeSansBold.otf
```

Start with cont/CMakeLists.txt at the linked generated springsettings.cfg section and inspect the Docker build scripts that invoke install. Check how the /build/out and /build/src/cont paths are exposed to the host, then verify that the executable from build output runs without the install step and that its generated settings resolve correctly.

Written by the indexing model from the issue text.