Editor - add separate controls for displaying x, y axis titles; add x, y axis custom titles

[geoerika]

Problem:

• some charts in the Cox app require hiding the x-axis title and show only the y-axis title
• also, some charts require custom y-axis titles
• none of this is possible currently with Widget Studio editor

Solution:

• add separate switches to hide/display x/y axis titles
• add textfields for custom x/y titles