fix(devtools): accept json file in import fileinput (#22717)

Author: jyash97

packages/react-devtools-shared/src/devtools/views/Profiler/ProfilingImportExportButtons.js

@@ -122,6 +122,7 @@ export default function ProfilingImportExportButtons() {
         ref={inputRef}
         className={styles.Input}
         type="file"
+        accept=".json"
         onChange={
           selectedTabID === 'timeline'
             ? importTimelineDataWrapper

packages/react-devtools-timeline/src/ImportButton.js

@@ -46,6 +46,7 @@ export default function ImportButton({children = null, onFileSelect}: Props) {
         ref={inputRef}
         className={styles.Input}
         type="file"
+        accept=".json"
         onChange={handleFiles}
         tabIndex={-1}
       />