fix(linter): fix line endings handling in '@nx/eslint:convert-to-flat-config' generator (#31043)

## Current Behavior

When running `nx g @nx/eslint:convert-to-flat-config` on windows, the
ignores path is not handled correctly. After converting, the path will
have the additional `/r`

## Expected Behavior

When running `nx g @nx/eslint:convert-to-flat-config` on windows, the
ignores path should be correct.

Author: Teamop

packages/eslint/src/generators/convert-to-flat-config/converters/json-converter.spec.ts

@@ -1,6 +1,7 @@
 import { Tree, readJson } from '@nx/devkit';
 import { createTreeWithEmptyWorkspace } from '@nx/devkit/testing';
 import { convertEslintJsonToFlatConfig } from './json-converter';
+import { EOL } from 'node:os';
 
 describe('convertEslintJsonToFlatConfig', () => {
   let tree: Tree;
@@ -63,7 +64,7 @@ describe('convertEslintJsonToFlatConfig', () => {
         })
       );
 
-      tree.write('.eslintignore', 'node_modules\nsomething/else');
+      tree.write('.eslintignore', `node_modules${EOL}something/else`);
 
       const { content } = convertEslintJsonToFlatConfig(
         tree,
@@ -227,7 +228,7 @@ describe('convertEslintJsonToFlatConfig', () => {
         })
       );
 
-      tree.write('mylib/.eslintignore', 'node_modules\nsomething/else');
+      tree.write('mylib/.eslintignore', `node_modules${EOL}something/else`);
 
       const { content } = convertEslintJsonToFlatConfig(
         tree,
@@ -376,7 +377,7 @@ describe('convertEslintJsonToFlatConfig', () => {
         })
       );
 
-      tree.write('.eslintignore', 'node_modules\nsomething/else');
+      tree.write('.eslintignore', `node_modules${EOL}something/else`);
 
       const { content } = convertEslintJsonToFlatConfig(
         tree,
@@ -537,7 +538,7 @@ describe('convertEslintJsonToFlatConfig', () => {
         })
       );
 
-      tree.write('mylib/.eslintignore', 'node_modules\nsomething/else');
+      tree.write('mylib/.eslintignore', `node_modules${EOL}something/else`);
 
       const { content } = convertEslintJsonToFlatConfig(
         tree,

packages/eslint/src/generators/convert-to-flat-config/converters/json-converter.ts

@@ -185,7 +185,7 @@ export function convertEslintJsonToFlatConfig(
     if (tree.exists(ignorePath)) {
       const patterns = tree
         .read(ignorePath, 'utf-8')
-        .split('\n')
+        .split(/\r\n|\r|\n/)
         .filter((line) => line.length > 0 && line !== 'node_modules')
         .map((path) => mapFilePath(path));
       if (patterns.length > 0) {