TechDraw: Area in mm² is not convenient (Add the ability to change the units of area measurement)

### Is there an existing issue for this?

- [X] I have searched the existing issues

### Problem description

When measuring area, the global unit of measure mm2 is used, and as a rule a value in m2 is required. It may be worth adding the ability to select the area units in the measurement properties and/or TechDraw settings


### Full version info

```shell
OS: Windows 11 build 26100
Architecture: x86_64
Version: 1.1.0dev.39646 (Git) Conda
Build type: Release
Branch: main
Hash: b25b83c1a58bf0ae95cbd502d0ccae27e8127cad
Python 3.11.11, Qt 5.15.15, Coin 4.0.3, Vtk 9.3.0, OCC 7.8.1
Locale: Russian/Russia (ru_RU)
Stylesheet/Theme/QtStyle: FreeCAD Dark.qss/FreeCAD Dark/Fusion
Installed mods:
* Curves 0.6.52
* fasteners 0.5.33
* PieMenu 1.10.2
* sheetmetal 0.6.2
```

### Subproject(s) affected?

TechDraw

### Anything else?

_No response_

### Code of Conduct

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

Review the TechDraw measurement properties and settings described in the issue, along with the comment discussion, to determine the intended unit-selection location and supported area units. Done means area measurements can be displayed in a user-selected unit such as m² instead of only mm², with the behavior agreed in the thread.

Written by the indexing model from the issue text.