Jobsets: The Dialog 'Export 3D Model Job Settungs' accept not relative paths

Description

The 'Export 3D Model Job Settungs' dialog always creates absolute paths when saving. This means that the job set export does not work.

Steps to reproduce

1. Create a Jobset
2. Add a 3D model export job
3. Type in the filename field a relative path
4. Click on OK
5. Open the setting from this job again

KiCad Version

Application: KiCad x86_64 on x86_64

Version: 9.0.0-rc1-431-g39ab530db3-dirty, debug build

Libraries:
	wxWidgets 3.2.4
	FreeType 2.13.2
	HarfBuzz 8.5.0
	FontConfig 2.15.0
	libcurl/8.6.0 OpenSSL/3.2.2 zlib/1.3.1.zlib-ng brotli/1.1.0 libidn2/2.3.7 libpsl/0.21.5 libssh/0.10.6/openssl/zlib nghttp2/1.59.0 OpenLDAP/2.6.8

Platform: Fedora Linux 40 (Cinnamon), 64 bit, Little endian, wxGTK, X11, cinnamon, x11
OpenGL: Mesa, llvmpipe (LLVM 18.1.6, 256 bits), 4.5 (Compatibility Profile) Mesa 24.1.7

Build Info:
	Date: Jan  6 2025 16:10:54
	wxWidgets: 3.2.4 (wchar_t,wx containers) GTK+ 3.24
	Boost: 1.83.0
	OCC: 7.6.3
	Curl: 8.6.0
	ngspice: 43
	Compiler: GCC 14.2.1 with C++ ABI 1019

Build settings:
	KICAD_IPC_API=ON
	KICAD_STDLIB_DEBUG=OFF
	KICAD_STDLIB_LIGHT_DEBUG=OFF
	KICAD_SANITIZE_ADDRESS=OFF
	KICAD_SANITIZE_THREADS=OFF

Locale: 
	Lang: de_DE
	Enc: UTF-8
	Num: 1.234,5
	Encoded кΩ丈: D0BACEA9E4B888 (sys), D0BACEA9E4B888 (utf8)