Add columns per breakpoint setting for single columns

Problem/Motivation

Sometimes its required to have more granular control about the column widths used on a specific device size.

Example 1: 3 Column Layout with very long words getting cut off, because of the low default column width on size 'medium'
=> Set Medium to 6/12 or 12/12 columns

Example 2: 3 Column Layout with just icons and a short buzzword, each cell becomes 100% width (12/12 columns), what doesn't look good and allocates to much space
=> Set Small to 4/12, so the icons are stay next each other

So this is a problem in both directions. The default lives somewhere in the middle of those examples.

Example 3: Nested layouts: No matter what the default column widths are, those layouts will break 100%.

Proposed resolution

Add options to override DROWL Layouts column sizes by device size.

The easier way: Equal width for all columns
Required fields:

• Small Columns
• Medium Columns
• Large Columns

The complicated way: Custom width for each column (allows more complex layouts)
Required fields:

• Column 1
  • Small Columns
  • Medium Columns
  • Large Columns
• Column 2
  • Small Columns
  • Medium Columns
  • Large Columns
• Column 3
  • Small Columns
  • Medium Columns
  • Large Columns
• Column ...

In this case, the column width options should be something like (per Device Size):
- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- auto (fill remaining space)
- min-content
- (max-content?)

Remaining tasks

User interface changes

API changes

Data model changes