[Problem] Draft array tool does not allow use of expressions during initial creation

### Is there an existing issue for this?

- [X] I have searched the existing issues

### Problem description

The draft array tool is inconsistent in that it does not allow expressions during initial creation, even though they can be used by modifying the properties of the array after creation.

### Full version info

```shell
[code]
OS: Windows 10 build 19045
Word size of FreeCAD: 64-bit
Version: 0.21.0.33668 +7 (Git)
Build type: Release
Branch: (HEAD detached at 0.21)
Hash: 41b058e2087de60dc8fef3d3e68c7d0129e13abf
Python 3.8.10, Qt 5.15.2, Coin 4.0.1, Vtk 8.2.0, OCC 7.6.3
Locale: English/United States (en_US)
Installed mods:
* Assembly4 0.50.2
[/code]
```

### Subproject(s) affected?

Draft

### Anything else?

No expressions allowed here

Expressions work fine when modifying properties

### Code of Conduct

- [X] I agree to follow this project's Code of Conduct

Start by locating the Draft array tool's initial-creation workflow and the property-editing path that already accepts expressions. Compare how expressions are handled in those two paths, then verify that expressions are accepted during initial creation without breaking ordinary array creation.

Written by the indexing model from the issue text.