Automatically show the best chart visualisation

When users select the line chart, they should automatically be given the best visualisation possible:
Time should be preferred as category axis if >1 time is selected

Note
The "Improve table layout" button is not modified to also work in chart mode. We decided to create a issue of its own for this. #184

Acceptance criteria
When selecting the line chart you automatically get the best visualisation (based on rules)

Test
Verify that chart is displayed in the expected way with time on the x-axis.
Also verify that table (both desktop and mobile) still is displayed in the expected way.
Verify that pivoting works as expected. Switch between the different presentation views (desktop-/mobile table and chart) and verify that pivoting works as expected in all of the views.
Change the selection. Add and remove variables and values. Change codelists. Switch between presentation views and verify that it works as expected.
Note! Charts can only be tested using the swedish test links since charts are still not enabled in the norwegian configuration file.
Question: What shall happen if we have no time variable?