[ui] Fix config dialog scrolling (#16975)

## Summary & Motivation

Some recent CodeMirror changes led to the config dialogs being
unscrollable. Repair this by setting a height and overflow style on the
CodeMirror target div.

## How I Tested These Changes

View config dialogs (code location config, run config), Deployment
configuration page, launchpad. Verify that CodeMirror containers are
properly scrollable.

js_modules/dagster-ui/packages/ui-components/src/components/RawCodeMirror.tsx

@@ -81,5 +81,5 @@ export const RawCodeMirror = (props: Props) => {
     }
   }, [options]);
 
-  return <div ref={target} />;
+  return <div style={{height: '100%', overflow: 'hidden'}} ref={target} />;
 };

js_modules/dagster-ui/packages/ui-core/src/instance/InstanceConfig.tsx

@@ -88,12 +88,15 @@ export const InstanceConfig = React.memo(() => {
           Dagster version: <Code style={{fontSize: '16px'}}>{data.version}</Code>
         </Subheading>
       </Box>
-      <StyledRawCodeMirror
-        value={config || ''}
-        options={{readOnly: true, lineNumbers: true, mode: 'yaml'}}
-        handlers={handlers}
-        theme={['instance-config']}
-      />
+      {/* Div wrapper on CodeMirror to allow entire page to scroll */}
+      <div>
+        <StyledRawCodeMirror
+          value={config || ''}
+          options={{readOnly: true, lineNumbers: true, mode: 'yaml'}}
+          handlers={handlers}
+          theme={['instance-config']}
+        />
+      </div>
     </>
   );
 });