feat(developer): Multi-select and add action/command for touch layout editor

**Is your feature request related to a problem? Please describe.**
When a particular attribute is to be applied to a number of items, one should be able to select all the items and then apply that action once, and it should affect all the items.

**Describe the solution you'd like**
I should be able to select a number of keys on the keyboard and apply a given attribute to all those keys at once. Eg. Select all the keys in a row, and type in a value for the key button width