When a power signal is added, such as P(R1), we need to add a watt axis to the graph

Description

We have a SPT_POWER signal type (which gets assigned to m_axis_y3), but it doesn't appear to get added when you add P(xx) by hand. Or maybe it just doesn't in a DC analysis? See https://forum.kicad.info/t/showing-op-voltage-and-current-data-in-eeschema-v7-99-nightly-builds-how/40331/9

KiCad Version

Application: KiCad Schematic Editor x86_64 on x86_64

Version: 7.99.0-1.20230221git543a331.fc37, release build

Libraries:
wxWidgets 3.2.1
FreeType 2.12.1
HarfBuzz 5.2.0
FontConfig 2.14.1
libcurl/7.85.0 OpenSSL/3.0.8 zlib/1.2.12 brotli/1.0.9 libidn2/2.3.4 libpsl/0.21.1 (+libidn2/2.3.3) libssh/0.10.4/openssl/zlib nghttp2/1.51.0

Platform: Fedora release 37 (Thirty Seven), 64 bit, Little endian, wxGTK, KDE, wayland

Build Info:
Date: Feb 21 2023 18:17:26
wxWidgets: 3.2.1 (wchar_t,wx containers) GTK+ 3.24
Boost: 1.78.0
OCC: 7.6.3
Curl: 7.85.0
ngspice: 39
Compiler: GCC 12.2.1 with C++ ABI 1017

Build settings:
KICAD_SPICE=ON