Feature request: linear frequency axis plot for ngspice AC simulation (ac lin number start stop)

Description

• When requesting a linear ac simulation (ngspice using ".ac lin number fstart fstop in the schematic text), the output is displayed in a logarithmic scale. The expected behaviour would be to plot the output of the calculation in a linear frequency scale.

Steps to reproduce

• Create a RC circuit including a Spice Vsin source and a text stating ".ac lin Numpoints fstart fstop", see attached screenshot
• Run the simulation, select the line above C1//R2 as the signal to plot

See https://groups.io/g/kicad-users/message/23871 confirming the issue is valid on KiCAD 8

KiCad Version

Application: KiCad Schematic Editor x86_64 on x86_64

Version: 7.0.11+dfsg-1, release build

Libraries: wxWidgets 3.2.4 FreeType 2.13.2 HarfBuzz 8.3.0 FontConfig 2.15.0 libcurl/8.5.0 OpenSSL/3.1.4 zlib/1.3 brotli/1.1.0 zstd/1.5.5 libidn2/2.3.4 libpsl/0.21.2 (+libidn2/2.3.4) libssh2/1.11.0 nghttp2/1.58.0 librtmp/2.3 OpenLDAP/2.5.13

Platform: Debian GNU/Linux trixie/sid, 64 bit, Little endian, wxGTK, lightdm-xsession, x11

Build Info: Date: Feb 23 2024 17:59:55 wxWidgets: 3.2.4 (wchar_t,wx containers) GTK+ 3.24 Boost: 1.83.0 OCC: 7.6.3 Curl: 8.6.0 ngspice: 42 Compiler: GCC 13.2.0 with C++ ABI 1018

Build settings: KICAD_SPICE=ON