[eslint] Add `import/first` rule.

I was sure we already had this rule, but somehow we didn't. We should of
course strive to have `import` statements first in all files.

Bug: none
Change-Id: Ic583710adc6cb3b7e5c0ae4bd82cd1f31fc9442b
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/6219315
Reviewed-by: Nikolay Vitkov <[email protected]>
Auto-Submit: Benedikt Meurer <[email protected]>
Commit-Queue: Benedikt Meurer <[email protected]>
diff --git a/eslint.config.mjs b/eslint.config.mjs
index 840e3d5..ef0d45f 100644
--- a/eslint.config.mjs
+++ b/eslint.config.mjs
@@ -249,6 +249,8 @@
       'no-implicit-globals': 'off',
       'no-unused-private-class-members': 'error',
 
+      // Sort imports first
+      'import/first': 'error',
       // Closure does not properly typecheck default exports
       'import/no-default-export': 'error',
       /**