qt: More error handling and tweaking to OpenGL 3 renderer

[ts-korhonen]

Summary

• Improve error handling and add more checks to initialization.
• Request 3.2 core profile context instead of 3.0; this doesn't mean raising the requirement as Qt will still provide the closest matching version, but requesting lower that 3.2 will not give core profile even if it was supported by the system.

Checklist

• Closes #xxx
• I have discussed this with core contributors already
• This pull request requires changes to the ROM set
  • I have opened a roms pull request - https://github.com/86Box/roms/pull/changeme/

References

Provide links to datasheets or other documentation that helped you implement this pull request.