feat(v2): docs versioning ❄️🔥 (#1983)

* wip: versioning

* wip again

* nits lint

* refactor metadata code so that we can have inobject properties optimization, fix typing

* remove buggy permalink code

* modify versioned docs fixture such that foo/baz only exists in v1.0.0

* refactor metadata.ts so that there is less transformon object

* more refactoring

* reduce test fixtures, refactoring

* refactoring readability

* finish metadata part

* refactor with readdir

* first pass of implementation

* fix mdx laoder

* split generated routes by version for performance & smaller bundle

* test data for demo

* refactor with set

* more tests

* typo

* fix typo

* better temporary ui

* stronger typing & docsVersion command

* add 100% test coverage for docsVersion command

* more test and delete manual docs cut

* cut 2.0.0-alpha.35 docs

* cut alpha.36 instead

* copyright

* delete versioned docs

* stronger test on metadata

* update typo

packages/docusaurus-plugin-content-docs/src/__tests__/order.test.ts

@@ -230,32 +230,6 @@ describe('createOrder', () => {
     });
   });
 
-  test('multiple sidebars with unknown sidebar item type', () => {
-    expect(() =>
-      createOrder({
-        docs: [
-          {
-            type: 'category',
-            label: 'Category1',
-            items: [
-              {type: 'endi', id: 'doc1'},
-              {type: 'doc', id: 'doc2'},
-            ],
-          },
-        ],
-        otherDocs: [
-          {
-            type: 'category',
-            label: 'Category1',
-            items: [{type: 'doc', id: 'doc5'}],
-          },
-        ],
-      }),
-    ).toThrowErrorMatchingInlineSnapshot(
-      `"Unknown item type: endi. Item: {\\"type\\":\\"endi\\",\\"id\\":\\"doc1\\"}"`,
-    );
-  });
-
   test('edge cases', () => {
     expect(createOrder({})).toEqual({});
     expect(createOrder(undefined)).toEqual({});