Add a `blocklyFieldText` CSS class to fields' text elements

[Beka Westberg]

In the field's createTextElement_ method, add a blocklyFieldText class to the class property.

blockly/core/field.ts

Line 376 in 8323642

 'class': 'blocklyText', 

[Gabriel Fleury]

Hey @BeksOmega, can you assign this to me?

[Beka Westberg]

Closed by #8302