feat(desktop): add highlighting on active topic and payload search

[muzaffarmhd]

PR Checklist

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What is the current behavior?

Currently, when searching through messages in MQTTX, there is no highlighting of matching text.

Issue Number

#1854

What is the new behavior?

The search functionality now highlights the active payload in message items.

Preview

Does this PR introduce a breaking change?

• [ ] Yes
• [x] No