Add delta/trend support to big number

### Provide a general summary of the feature here

Big numbers currently support sparklines and/or icons. We should add the ability to show a basic trend/delta (ie +4.5%) to big numbers.

### 🤔 Expected Behavior?

A new label option is added to big number—a basic delta.

### 💁 Possible Solution

_No response_

### 🔦 Context

AIA mocks make use of trends in the monitoring dashboard

### 💻 Examples

_No response_

### 🧢 Your Company/Team

AI Assistant

Start by locating the big number component and its existing label-option implementation, then review how sparklines and icons are exposed. Add support for a basic trend or delta such as +4.5%, and verify that the value renders correctly in the monitoring-dashboard use case.

Written by the indexing model from the issue text.