Add api page (#32)

# Changes

- Added [redocusaurus](https://github.com/rohit-gohri/redocusaurus) package to display swagger api with reference to [woodpecker](https://github.com/woodpecker-ci/woodpecker/tree/master/docs)
- Change `sed` for swagger.json for proper version and baseurl.
- Add a dropdown for different api versions. (screenshot below)
- On API pages, only API version dropdown will show(hide locale dropdown, version dropdown for doc, and doc search)
- Allow build CSR API pages for development so it saves building time.

# Screenshots

![Screen Shot 2023-06-27 at 11.56.59](/attachments/7f43976d-f9f1-42ff-85f5-0bc84e549441)

![Screen Shot 2023-06-27 at 10.58.11](/attachments/bde25da5-b0a6-4908-9c69-c6aed41f8f59)

![Screen Shot 2023-06-21 at 12.26.26](/attachments/84a9bf5a-229b-4031-9654-3bae6cb3301a)

![Screen Shot 2023-06-19 at 16.34.33](/attachments/653b2b59-bc8a-4e6c-82f2-eb9710f55d8d)

Search:

![Screen Shot 2023-06-21 at 14.49.15](/attachments/3a09bd89-36a8-4156-a2df-2d3176d3ddb1)

Reviewed-on: https://gitea.com/gitea/gitea-docusaurus/pulls/32
Co-authored-by: HesterG <hestergong@gmail.com>
Co-committed-by: HesterG <hestergong@gmail.com>

src/pages/api/1.19/index.js

@@ -0,0 +1,8 @@
+import React from 'react';
+import ClientOnly from '@site/src/components/ClientOnly';
+
+export default function Api19() {
+  return (
+    <ClientOnly swaggerPath="/swagger-19.json"/>
+  );
+}

src/pages/api/1.20/index.js

@@ -0,0 +1,8 @@
+import React from 'react';
+import ClientOnly from '@site/src/components/ClientOnly';
+
+export default function Api20() {
+  return (
+    <ClientOnly swaggerPath="/swagger-20.json"/>
+  );
+}

src/pages/api/next/index.js

@@ -0,0 +1,8 @@
+import React from 'react';
+import ClientOnly from '@site/src/components/ClientOnly';
+
+export default function ApiLatest() {
+  return (
+    <ClientOnly swaggerPath="/swagger-latest.json"/>
+  );
+}