improvement idea for spreadsheet generator

[Crare]

Could you add a total number to that generation window and a percentage of completion? This is taking a long time and I would like to see how far it's from completion.

Image below shows what it currently looks like when generating spreadsheet. This is just a minor improvement, but it would be much appreciated.

[FxKu]

What do you think @Son-HNguyen @yaozhihang ? Sounds not too hard to implement.

[Son-HNguyen]

Added in 3dcitydb/plugin-spreadsheet-generator@c732276. The pop-up window now shows the total number of elements to be exported and the progress bars now also displays the percentage accordingly.