Allow dynamic expressions in "maxCount" for Repeating groups

### Description

For a repeating group, sometimes the maximum number of elements are 1 and sometimes they are unlimited. I would love to have a feature to add this logic directly to the component
```json
"maxCount": [
"if",
[
"equals",
["dataModel", "only1choice"],
true,
],
1,
"else",
999
],
```

### Additional Information

_No response_

No file or test is identified in the issue. Start by locating repeating-group handling and the maxCount entry point in the TypeScript frontend, then compare the requested expression shape with current behavior; done means maxCount can resolve the shown condition to either 1 or an effectively unlimited value.

Written by the indexing model from the issue text.