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/FieldSource.tsx

@@ -0,0 +1,35 @@
+import React from 'react'
+
+import {latest} from '@maplibre/maplibre-gl-style-spec'
+import Block from './Block'
+import InputAutocomplete from './InputAutocomplete'
+
+type FieldSourceProps = {
+  value?: string
+  wdKey?: string
+  onChange?(...args: unknown[]): unknown
+  sourceIds?: unknown[]
+  error?: unknown[]
+};
+
+export default class FieldSource extends React.Component<FieldSourceProps> {
+  static defaultProps = {
+    onChange: () => {},
+    sourceIds: [],
+  }
+
+  render() {
+    return <Block
+      label={"Source"}
+      fieldSpec={latest.layer.source}
+      error={this.props.error}
+      data-wd-key={this.props.wdKey}
+    >
+      <InputAutocomplete
+        value={this.props.value}
+        onChange={this.props.onChange}
+        options={this.props.sourceIds?.map(src => [src, src])}
+      />
+    </Block>
+  }
+}