Tree widget: Tree load takes too much time when a lot of elements are selected with instance focus mode enabled

[grigasp]

http://localhost:3000/?iTwinId=b391ba44-add7-47a0-8375-f2889a3540e8&iModelId=ba504f88-a479-4156-9d81-658ee169588e

1. Open stateless models tree
2. Enable focus mode
3. Fence-select all elements in the viewport

Result:

TreeWidget [models-tree-v2-reload] took 23443 ms

[grigasp]

This happens because we attempt to filter the hierarchy based on a very large number of instance keys. There's a similar situation if you try to filter a string that's contained in many node labels, e.g. "a".

IMO, the solution is to prohibit filtering the hierarchy by more than 100 number of instance keys.

• In focus mode, we get instance keys from selection, so we can immediately do the check.
• In filter by label case, we run a query to get target instance keys and then, possibly, run queries to get instance key paths. Ideally, we should avoid doing the second part if we get too many target instance keys. In fact, the target instance keys lookup query should have LIMIT 101 to avoid querying too much unnecessarily.

[grigasp]

Related: https://github.com/iTwin/viewer-components-react/issues/908.