improve styling for linked image profiles

[Andreas Janz]

Discussed with AO, BJ, AR via Zoom

usecase:

• I have 3 raster sources linked into one spectral view
• I want to set the profile style (i.e. color, thick, symbol) for each source
• I now want to explore the raster profiles at different locations (by clicking around in a map view) → the 3 profiles should be plotted with their according styles

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[Benjamin Jakimow]

qps updates: - updated licence notes - added band number to spectral profile plot (closes #267 ) - added SpectralProfileRenderer, refactored profile style system (addresses #422) - profile styles are saved / loaded from layer style qml files - SpectralLibraries can be better saved/loaded to/from gpkg, geojson, csv

→ <<cset 621620102569>>

[Benjamin Jakimow]

spectralprofilesources.py and related GUI files - added default plot style to each profile source (addresses issue #422)

→ <<cset e41ecf290153>>