Allow different selection styles and highlight styles for specific layers

[steff-o]

Is your feature request related to a problem? Please describe. When selecting many features from different layers, all features use the same selection symbol (With the exception of those using inActiveLayer and highlighted symbols)

Describe the solution you'd like It should be possible to configure for each layer a symbol for different occasions:

1. Normal symbol
2. Selected symbol
3. Selected in active group
4. Highlighted

Alternatively it should be possible to configure layer specific symbols using the multiSelectionStyles setting

Another alternative would be allowing layername filters on ordinary symboldefinitions, so the existing multiSelectionStyles.inActiveLayer and multiSelectionStyles.highlighted settings could be used but that would probably be pretty messy to configure.

Describe alternatives you've considered

1. Add a column with its type to each participating layer and use a normal thematic style filter on the symbols in multiSelectionStyles.inActiveLayer and multiSelectionStyles.highlighted, but that requires modifying data.
2. Using a custom symbol function that checks the layer name, but that requires coding.

Additional context Sorry, no screenshots...