feat: preserve EOL in files (#16087)

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>
Co-authored-by: Adib234 <30782825+Adib234@users.noreply.github.com>
Co-authored-by: Jack Wotherspoon <jackwoth@google.com>

packages/core/src/tools/write-file.test.ts

@@ -901,6 +901,7 @@ describe('WriteFileTool', () => {
         errorMessage: 'Generic write error',
         expectedMessagePrefix: 'Error writing to file',
         mockFsExistsSync: false,
+        restoreAllMocks: false,
       },
     ])(
       'should return $errorType error when write fails with $errorCode',