Migration of jsx files to tsx 2 (#850)

This is to continue the work of migrating all the jsx files into tsx
files.
The MO is basically described here: #848.

About 7 files to go...

src/components/LayerListGroup.tsx

@@ -0,0 +1,34 @@
+import React from 'react'
+import Collapser from './Collapser'
+
+type LayerListGroupProps = {
+  title: string
+  "data-wd-key"?: string
+  isActive: boolean
+  onActiveToggle(...args: unknown[]): unknown
+  'aria-controls'?: string
+};
+
+export default class LayerListGroup extends React.Component<LayerListGroupProps> {
+  render() {
+    return <li className="maputnik-layer-list-group">
+      <div className="maputnik-layer-list-group-header"
+        data-wd-key={"layer-list-group:"+this.props["data-wd-key"]}
+        onClick={_e => this.props.onActiveToggle(!this.props.isActive)}
+      >
+        <button
+          className="maputnik-layer-list-group-title"
+          aria-controls={this.props['aria-controls']}
+          aria-expanded={this.props.isActive}
+        >
+          {this.props.title}
+        </button>
+        <span className="maputnik-space" />
+        <Collapser
+          style={{ height: 14, width: 14 }}
+          isCollapsed={this.props.isActive}
+        />
+      </div>
+    </li>
+  }
+}