Plot UV/Vis and CD spectra from ORCA 6 output

[stanpapa]

Avogadro version:

• Avogadrolibs: 1.100.0
• Qt: 6.8.1

Is your feature request related to a problem? Please describe.
Not sure if this is a bug report or a feature request. I can see in the source code that the UV/Vis and CD spectra are read from an ORCA 6 output file, but the spectra cannot be plotted. The option Analysis > Import Spectra is greyed out when opening an ORCA output file. This can be reproduced on both Linux and macOS with the release binaries

Should Avogadro be able to plot these spectra or will this be a new feature? It would be a great if Avogadro could add this functionality.

Additional context
In order to generate UV/Vis + CD specra, one can use the following input

! B3LYP def2-SVP

%tddft
  NRoots 10
end

* xyz 0 1
C     -0.82081    0.98705    0.00000
Cl    -0.02081    0.73868    0.66575
F     -0.49821    1.75138   -0.67574
Br    -1.10610    0.11771   -0.55475
H     -1.65812    1.34044    0.56475
* 

The relevant sections of the output file are

----------------------------------------------------------------------------------------------------
                     ABSORPTION SPECTRUM VIA TRANSITION ELECTRIC DIPOLE MOMENTS    
----------------------------------------------------------------------------------------------------
     Transition      Energy     Energy  Wavelength fosc(D2)      D2        DX        DY        DZ   
                      (eV)      (cm-1)    (nm)                 (au**2)    (au)      (au)      (au)  
----------------------------------------------------------------------------------------------------
  0-1A  ->  1-1A    3.511683   28323.6   353.1   0.009174354   0.10664  -0.23827  -0.08292  -0.20733
  0-1A  ->  2-1A    6.109826   49279.1   202.9   0.097859017   0.65375   0.29912   0.51948   0.54260
  0-1A  ->  3-1A    7.185688   57956.5   172.5   0.162332227   0.92210  -0.78952   0.46152   0.29286
  0-1A  ->  4-1A    7.848729   63304.3   158.0   0.011900174   0.06189   0.15350  -0.19321   0.03154
  0-1A  ->  5-1A    8.470928   68322.7   146.4   0.022589886   0.10885  -0.02752  -0.25687  -0.20520
  0-1A  ->  6-1A    9.274867   74806.9   133.7   0.027124300   0.11937   0.12396  -0.25562   0.19663
  0-1A  ->  7-1A    9.962535   80353.3   124.5   0.027537842   0.11282   0.26261   0.19202  -0.08359
  0-1A  ->  8-1A   10.528298   84916.5   117.8   0.088376462   0.34263  -0.41322   0.31139  -0.27370
  0-1A  ->  9-1A   10.807063   87164.9   114.7   0.009974325   0.03767  -0.13135  -0.12515   0.06896
  0-1A  -> 10-1A   11.030280   88965.2   112.4   0.030120755   0.11146   0.26616   0.09899   0.17555

...

------------------------------------------------------------------------------------------
                     CD SPECTRUM VIA TRANSITION ELECTRIC DIPOLE MOMENTS    
------------------------------------------------------------------------------------------
     Transition      Energy     Energy  Wavelength    R        MX        MY        MZ   
                      (eV)      (cm-1)    (nm)   (1e40*cgs)   (au)      (au)      (au)  
------------------------------------------------------------------------------------------
  0-1A  ->  1-1A    3.511683   28323.6   353.1    2.76031   0.07458  -0.29350   0.05991
  0-1A  ->  2-1A    6.109826   49279.1   202.9    8.06752  -0.08210   0.21864  -0.19560
  0-1A  ->  3-1A    7.185688   57956.5   172.5   30.74285   0.02619  -0.04581  -0.07988
  0-1A  ->  4-1A    7.848729   63304.3   158.0  -23.94958   0.71616   0.18898  -0.71725
  0-1A  ->  5-1A    8.470928   68322.7   146.4   19.77268  -0.11629   0.20276  -0.03384
  0-1A  ->  6-1A    9.274867   74806.9   133.7  -16.55748   0.17252   0.14278   0.25546
  0-1A  ->  7-1A    9.962535   80353.3   124.5    1.91172  -0.18736   0.27251   0.08590
  0-1A  ->  8-1A   10.528298   84916.5   117.8   13.28660  -0.08539  -0.11028   0.10642
  0-1A  ->  9-1A   10.807063   87164.9   114.7   -2.69131   0.34712  -0.28946   0.21862
  0-1A  -> 10-1A   11.030280   88965.2   112.4  -38.49008   0.36535   0.13605  -0.16558