Unite icons (#1374)

## Launch Checklist

This removes the `@mdi` (material design icons) package and uses the
icons from `react-icons`.
The icons are not exactly the same, but have the same idea behind them.

 - [x] Briefly describe the changes in this PR.
- [x] Include before/after visuals or gifs if this PR includes visual
changes.
 - [x] Add an entry to `CHANGELOG.md` under the `## main` section.

Main changes can be found below.
Before:
<img width="580" height="780" alt="image"
src="https://github.com/user-attachments/assets/e3d5fc8a-bd59-48fe-bdae-31bb290749c8"
/>


After:

<img width="580" height="780" alt="image"
src="https://github.com/user-attachments/assets/bacdbdba-9e73-4bef-bd30-26fe946269c1"
/>

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

src/components/_ZoomProperty.tsx

@@ -1,5 +1,6 @@
 import React from "react";
-import {mdiFunctionVariant, mdiTableRowPlusAfter} from "@mdi/js";
+import { PiListPlusBold } from "react-icons/pi";
+import { TbMathFunction } from "react-icons/tb";
 import latest from "@maplibre/maplibre-gl-style-spec/dist/latest.json";
 import { type WithTranslation, withTranslation } from "react-i18next";
 
@@ -233,17 +234,15 @@ class ZoomPropertyInternal extends React.Component<ZoomPropertyInternalProps, Zo
               className="maputnik-add-stop"
               onClick={this.props.onAddStop?.bind(this)}
             >
-              <svg style={{width:"14px", height:"14px", verticalAlign: "text-bottom"}} viewBox="0 0 24 24">
-                <path fill="currentColor" d={mdiTableRowPlusAfter} />
-              </svg> {t("Add stop")}
+              <PiListPlusBold style={{ verticalAlign: "text-bottom" }} />
+              {t("Add stop")}
             </InputButton>
             <InputButton
               className="maputnik-add-stop"
               onClick={this.props.onExpressionClick?.bind(this)}
             >
-              <svg style={{width:"14px", height:"14px", verticalAlign: "text-bottom"}} viewBox="0 0 24 24">
-                <path fill="currentColor" d={mdiFunctionVariant} />
-              </svg> {t("Convert to expression")}
+              <TbMathFunction style={{ verticalAlign: "text-bottom" }} />
+              {t("Convert to expression")}
             </InputButton>
           </div>
         </div>