### Describe the bug

libraries like axios-mock-adapter define an adapter but in same cases need to access to original adapter.

It was working correctly before as the adapter was always a function.
Now it can be an array of string

Only the method getAdapter() in adapters/adapter.js can allow access to original adapters (xhr and http)
But this method is not exported a all at top level.

Can you export it ? 


### To Reproduce

Try to use axios-mock-adapter plugin with onNoMatch option

### Code snippet

_No response_

### Expected behavior

_No response_

### Axios Version

1.2.1 and upper

### Adapter Version

_No response_

### Browser

_No response_

### Browser Version

_No response_

### Node.js Version

_No response_

### OS

_No response_

### Additional Library Versions

_No response_

### Additional context/Screenshots

_No response_
test/module/typings/esm/index.ts
}
});
axios.get('/user', {
  adapter: 'xhr'
});
axios.get('/user', {
  adapter: 'http'
});
axios.get('/user', {
  adapter: ['xhr', 'http']
});
const headers = new AxiosHeaders({foo: "bar"})
for (const [header, value] of headers) {
  console.log(header, value);
}
(()=>{
  const headers = new AxiosHeaders({x:1});
  headers.y = 2;
})();
(()=>{
  const headers:AxiosRequestHeaders = new AxiosHeaders({x:1});
  headers.y = 2;
  headers.get('x');
})();
{
  const requestInterceptorId: number = axios.interceptors.request.use(
      async (config) => {
        config.headers.Accept ="foo";
        config.headers.setAccept("foo");
        config.headers = new AxiosHeaders({x:1});