fix[utils]: param2Obj bug when url params includes ==(#3100)

tests/unit/utils/param2Obj.spec.js

@@ -0,0 +1,14 @@
+import { param2Obj } from '@/utils/index.js'
+describe('Utils:param2Obj', () => {
+  const url = 'https://github.com/PanJiaChen/vue-element-admin?name=bill&age=29&sex=1&field=dGVzdA==&key=%E6%B5%8B%E8%AF%95'
+
+  it('param2Obj test', () => {
+    expect(param2Obj(url)).toEqual({
+      name: 'bill',
+      age: '29',
+      sex: '1',
+      field: window.btoa('test'),
+      key: '测试'
+    })
+  })
+})