Differential pair length tuning tool doesn't allow to customize radius.

In the differential pair length tuning dialog, it is not possible to change the radius of the differential pairs.

As a result, if the spacing and amplitude are too large, the serpentine looks like this:

Now we get in the territory of the art of PCB layout, but I think it would be generally recommended to have a bigger radius, as this would be a lesser disturbance. And it also makes sense to keep a significant spacing value to prevent coupling of the tracks. I would like to have something that resembles the actual picture of the dialog box.

The only advantage of the shown serpentine, is that it allows to extend the length more efficiently than a more round one. Which is useful in some cases, so it would make sense to keep this as a setting.

I think allowing to modify the miter radius setting and using it as the parameter to set the radius would be a good solution.

Application: KiCad PCB Editor x64 on x64

Version: 7.0.6, release build

Libraries:
	wxWidgets 3.2.2
	FreeType 2.12.1
	HarfBuzz 6.0.0
	FontConfig 2.14.1
	libcurl/7.88.1-DEV Schannel zlib/1.2.13

Platform: Windows 10 (build 19045), 64-bit edition, 64 bit, Little endian, wxMSW

Build Info:
	Date: Jul  6 2023 04:56:45
	wxWidgets: 3.2.2 (wchar_t,wx containers)
	Boost: 1.81.0
	OCC: 7.6.3
	Curl: 7.88.1-DEV
	ngspice: 40
	Compiler: Visual C++ 1936 without C++ ABI

Build settings:
	KICAD_SPICE=ON