What is the purpose of this pull request?

• New Icon

Description

Added new brick-wall-shield icon.

Icon use case

Added brick-wall-shield as an alternative firewall icon, as discussed in: #3036

Alternative icon designs

Icon Design Checklist

Concept

• I have provided valid use cases for each icon.
• I have not added any a brand or logo icon.
• I have not used any hate symbols.
• I have not included any religious or political imagery.

Author, credits & license

• The icons are solely my own creation.
• The icons were originally created in feat(icons): added brick-wall-fire icon #3036 by @karsa-mistmere
• I've based them on the following Lucide icons: brick-wall
• [] I've based them on the following design:

Naming

• I've read and followed the naming conventions
• I've named icons by what they are rather than their use case.
• I've provided meta JSON files in icons/[iconName].json.

Design

• I've read and followed the icon design guidelines
• I've made sure that the icons look sharp on low DPI displays.
• I've made sure that the icons look consistent with the icon set in size, optical volume and density.
• I've made sure that the icons are visually centered.
• I've correctly optimized all icons to three points of precision.

Before Submitting

• I've read the Contribution Guidelines.
• I've checked if there was an existing PR that solves the same issue.