New component 'SelectedTotal'

[lpatiny]

Currently in NMRium we have 5 different ways to display the number of selected items versus the total number of entries.

• Homogeneisation of selected / total cheminfo/nmrium#3234

We need a component to display this simple information (if it is not yet available) and the first place it should be used is:

I would suggest to always have [ selected / total ]. Take care that all the spaces are Thin Space (https://www.compart.com/en/unicode/U+2009)

Here is the difference between normal space and thin space

If selected is undefined we whould only display the total [ total ]

Once done it should be implemented in NMRium.