Description:
add ability to import/load styles in Calc as there is in Writer

In Writer i can load styles from existing document into my current document uses dialogue "Load styles" (SideBar > Styles > right top drop-down icon)
In that dialogue I can select a template, select type of styles for load.
I can also push button "From file.." and load all styles from existing Writer's file.

But in Calc there isn't this functional.

In Calc i can: 
1. create new cell style, 
2. apply new cell style to any cell, 
3. select it cell and copy it
4. open another spreadsheet and paste your cell
5. new cell style will show in style list in SideBar

But it is very uncomfortable

Steps to Reproduce:
1. try load cell styles in your spreadsheet from existing spreadsheet
2. 
3. 

Actual Results:  
in Calc there isn't functional load of styles .

Expected Results:
in Calc there is functional load of styles .


Reproducible: Always


User Profile Reset: No



Additional Info:


User-Agent: Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/66.0.3359.181 Safari/537.36