feat(eslint): relax frontend imports for nfs

allow frontend plugins to import from other frontend plugins with same
plugin id to allow plugin overrides without unnecessary eslint warning.

relates to #31372

Signed-off-by: Hellgren Heikki <heikki.hellgren@op.fi>

packages/eslint-plugin/src/__fixtures__/monorepo/packages/bar-override/package.json

@@ -0,0 +1,19 @@
+{
+  "name": "@internal/bar-override",
+  "backstage": {
+    "role": "frontend-plugin",
+    "pluginId": "bar"
+  },
+  "exports": {
+    ".": "./src/index.ts",
+    "./BarPage": "./src/components/Bar.tsx",
+    "./package.json": "./package.json"
+  },
+  "dependencies": {
+    "inline-dep": "*",
+    "react-router": "*"
+  },
+  "devDependencies": {
+    "react-router-dom": "*"
+  }
+}

packages/eslint-plugin/src/__fixtures__/monorepo/packages/bar/package.json

@@ -1,7 +1,8 @@
 {
   "name": "@internal/bar",
   "backstage": {
-    "role": "frontend-plugin"
+    "role": "frontend-plugin",
+    "pluginId": "bar"
   },
   "exports": {
     ".": "./src/index.ts",

packages/eslint-plugin/src/__fixtures__/monorepo/packages/foo/package.json

@@ -1,7 +1,8 @@
 {
   "name": "@internal/foo",
   "backstage": {
-    "role": "frontend-plugin"
+    "role": "frontend-plugin",
+    "pluginId": "foo"
   },
   "files": [
     "dist",