Codemirror 5 to 6 upgrade (#1386)

## Launch Checklist

- Resolves #891

This PR upgrades code mirror from version 5 to version 6.
It should not change any functionality dramatically.
The filter and other expressions have line numbers now as I was not able
to remove those without introducing a lot of code, which I preferred not
to.

Before:

<img width="571" height="933" alt="image"
src="https://github.com/user-attachments/assets/02f047ee-0857-4eb1-9431-2620099ea025"
/>


After:
<img width="571" height="933" alt="image"
src="https://github.com/user-attachments/assets/7cf60155-7cd9-4c06-915e-dec2ae8247fc"
/>



 - [x] Briefly describe the changes in this PR.
 - [x] Link to related issues.
- [x] Include before/after visuals or gifs if this PR includes visual
changes.
 - [x] Write tests for all new functionality.
 - [x] Add an entry to `CHANGELOG.md` under the `## main` section.

---------

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

src/components/LayerEditor.tsx

@@ -119,7 +119,7 @@ type LayerEditorInternalProps = {
   sources: {[key: string]: SourceSpecification & {layers: string[]}}
   vectorLayers: {[key: string]: any}
   spec: any
-  onLayerChanged(...args: unknown[]): unknown
+  onLayerChanged(index: number, layer: LayerSpecification): void
   onLayerIdChange(...args: unknown[]): unknown
   onMoveLayer: OnMoveLayerCallback
   onLayerDestroy(...args: unknown[]): unknown
@@ -280,8 +280,9 @@ class LayerEditorInternal extends React.Component<LayerEditorInternalProps, Laye
         />;
       case "jsoneditor":
         return <FieldJson
-          layer={this.props.layer}
-          onChange={(layer) => {
+          lintType="layer"
+          value={this.props.layer}
+          onChange={(layer: LayerSpecification) => {
             this.props.onLayerChanged(
               this.props.layerIndex,
               layer