Check button text empty before render button

Problem/Motivation

In Improved Multi Select, when the “Button text” field is left empty, the button is still rendered in the UI.

This results in:

• Empty or unclear buttons being displayed
• Poor user experience

Steps to reproduce

• Enable the module and configure a field with Improved Multi Select
• Leave the Button text field empty
• Save configuration and view the form
• Save configuration and view the form

Observe that the button is still displayed without proper text

Proposed resolution

• Do not render the button if Button text is empty
• Alternatively, enforce validation to require button text
• Ensure no empty/label-less buttons are output

Remaining tasks

Update render logic to conditionally display button

User interface changes

Buttons will not appear when text is empty

API changes

None

Data model changes

None