Tiktok support

Some OAuth2 providers have a slightly different implementation than the official specification.

If we take the case of TikTok's implementation, here are the differences in the URL parameters during the authorization procedure:

* The `client_id` parameter is named `client_key`.
* The `scope` parameter value is comma separated and **not URL encoded**.

It should be possible to specify how to change the parameters when generating the authorization URL, for example, by initializing it with new parameters:

```js
const result = await authorize({
customParameterNames: {
clientId: 'client_key'
...
},
encodeParameterValues: {
scope: false
},
staticAuthorizeUrl: 'https://example.com/authorize',
});
```
| Parameter | Type | Description |
| - | - | - |
| customParameterNames | **Object** | Specifies all parameters that should be renamed when generating the authorization URL. |
| encodeParameterValues | **Object** | Specifies all parameters that should be encoded or not when generating the authorization URL. |
| staticAuthorizeUrl | **String** | Specify to skip authorization URL generation and get this one |

Tiktok documentation :
https://developers.tiktok.com/doc/login-kit-web?enter_method=left_navigation

Any ideas?