[Problem] Creating a shapestring is difficult and confusing

### Is there an existing issue for this?

- [X] I have searched the existing issues

### Version

0.21 (Development)

### Full version info

```shell
[code]
OS: Linux Mint 20 (i3/i3)
Word size of FreeCAD: 64-bit
Version: 0.21.0.33029 +1 (Git)
Build type: Unknown
Branch: (HEAD detached at upstream/pr/9418)
Hash: bfcc5d029f2dfbce0be1c240363ef015dbd7d3c4
Python 3.8.10, Qt 5.12.8, Coin 4.0.0, Vtk 7.1.1, OCC 7.5.2
Locale: English/United States (en_US)
Installed mods:
* DynamicData 2.46.0
* Assembly4 0.12.5
* fasteners 0.4.55
* Behave-Dark-Colors 0.1.1
* 3DfindIT 1.2.0
* Render 2023.2.2
* ProDarkThemePreferencePack 1.0.0
* sheetmetal 0.2.59
* QuickMeasure 2022.10.28
* Nodes 0.1.36
* FeedsAndSpeeds 0.5.0
* Assembly3 0.11.4
* ExtremeProDark 2.6.4
* FeedsAndSpeeds.bak
* Curves 0.6.5
* A2plus 0.4.60k
* Dracula 0.0.2
[/code]
```

### Subproject(s) affected?

Draft

### Problem description

The ShapeString dialog is poorly designed and implemented. As a result, creating a shapestring is difficult and confusing.

Specific problems to be addressed in this issue:

The organization of the panel is unintuitive.

- The point is to create a string but the string input field is halfway down the task panel. It is the thing that is top-of-mind for the user so it should be the first input field.
- The font file should be the second input.
- The Height should be the third input.
- The string input feature contains default text of the word 'default' This should be a placeholder text with the string 'enter your string' or similar. As long as the string input field is unpopulated, the Apply/Ok buttons should be disabled.
- Font file input is unpopulated and requires the user to select a file rather than a font.
- 'reset point' control is confusing

The dialog does not provide realtime feedback. It should preview the shapestring in the 3D window

### Anything else?

Forum discussion:
https://forum.freecad.org/viewtopic.php?t=77718

### Code of Conduct

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

Start with the Draft ShapeString dialog and review the linked forum discussion for the current design context. Compare the existing control order, placeholder and button behavior, font-file selection, reset-point control, and 3D preview against the requested behavior. Done means the dialog is clearer to operate and provides realtime shapestring feedback.

Written by the indexing model from the issue text.