Disable brush in mags higher than mag8

[philippotto]

URL of deployed dev instance (used for testing):

• https://disablebrushinhighmags.webknossos.xyz

Steps to test:

• open a tracing, switch to brush tool
• ensure that brush is usable in mags 1 to 8
• the brush tool should get disabled (and another tool should be activated) automatically as soon as one zooms to an unusable mag

Issues:

• fixes Brushing in high mags (e.g., > mag 16) is slow #4967

---

• Updated (unreleased) changelog
• Updated (unreleased) migration guide if applicable
• Updated documentation if applicable
• Adapted wk-connect if datastore API changes
• Needs datastore update after deployment
• Ready for review

[daniel-wer]

Works like a charm, only two minor non-blocking suggestions :)

[daniel-wer]

One thing I noticed during testing is that this boolean is also false if the segmentation layer is simply disabled (for example, using 3). Could you adapt the message accordingly?

[philippotto]

Good catch! Since the existing logic around the disabled tool tooltip (i.e., which text to show) was a bit convoluted, I refactored the corresponding code which made it easier to integrate the case you mentioned. Also, the automatic switching of the tool (if the current one gets disabled), got a bit DRYer due to the refactoring.
Feel free to have another look!