Reduce draw distance when low on memory and OOM countermeasures

[akleshchev]

At the moment the only thing viewer can do when critically low on memory is to crash, suggestions:

• Accuratly track RAM usage and make it limit draw range when low.
• Consider other limits, like automatically limiting media draw range to be tighter than draw range
• On hardware with 4GB and less limit graphical quality and draw range or show a 'this might cause issues' notification when attempting to set those high
• Improve veiwer's memory profiling and then figure out what takes the most memory.

Goal

Reduce quantity of OOM crashes.

Testing

For synthetic testing you can increase RenderMinFreeMainMemoryThreshold

---

This repo is using Opire - what does it mean? 👇

💵 Everyone can add rewards for this issue commenting /reward 100 (replace 100 with the amount).
🕵️‍♂️ If someone starts working on this issue to earn the rewards, they can comment /try to let everyone know!
🙌 And when they open the PR, they can comment /claim #4604 either in the PR description or in a PR's comment.

🪙 Also, everyone can tip any user commenting /tip 20 @akleshchev (replace 20 with the amount, and @akleshchev with the user to tip).

📖 If you want to learn more, check out our documentation.