Add displayValue function to Expressions.

[framitdavid]

Looks up a component nearby, and presents its display value (which should work for number-formatted Input fields). See comment here: #1105 (comment)

We cannot use the useDisplayData method on the component directly within the expressions functions. This is primarily because useDisplayData may rely on hooks, causing React to crash if the number of hooks doesn't align with the previous render.

We need to figure out a solution for accessing the same data on the components without using hooks. I hope we can avoid implementing the same logic twice, with/out hooks.

[olemartinorg]

In a way, this is a duplicate of:

• As an app developer I want to show the display value as a variable in text #1105