## 🚀 Feature Proposal

Add support for the WebAuthn Automation API, a standard WebDriver extension that allows developers to create virtual authenticators to test websites using WebAuthn.

https://w3c.github.io/webauthn/#sctn-automation

_note: the above link may not work until https://github.com/w3c/webauthn/pull/1340 is merged_

## Motivation

At the moment there is no practical way to write e2e tests for pages using WebAuthn. Since this is a standard WebDriver API, the cost of implementing a layer on java is low.

## Example

For a page like this

```html
<button id="signup">Sign up with webauthn</button>
<span id="result"></span>
```

```javascript
document.getElmentById("signup").addEventListener("click", () => {
  navigator.credentials.create({...}).then(credentials => {
    document.getElementById("result").innerText = "Success!";
  })
});
```

A test could be written like so:

```java
// HasVirtualAuthenticator is an interface that augments a RemoteWebDriver.
HasVirtualAuthenticator virtualAuthenticatorManager = ((HasVirtualAuthenticator) driver);
VirtualAuthenticatorOptions options = new VirtualAuthenticatorOptions();
VirtualAuthenticator authenticator =
    virtualAuthenticatorManager.addVirtualAuthenticator(options);
driver.findElement(By.id("signup")).click();
WebElement result = driver.findElement(By.id("result"));
new WebDriverWait(driver, 60, 1000).until(
    driver -> !result.getText().equals(""));
assertThat(result.getText()).isEqualTo("Success!");
```

## Implementation

We can implement the AddVirtualAuthenticator and RemoveVirtualAuthenticator methods first since they're the most useful and follow up with the others in subsequent PRs.
@Override
  public <X> X getScreenshotAs(OutputType<X> outputType) throws WebDriverException {
    Response response = execute(DriverCommand.SCREENSHOT);
    Object result = response.getValue();
    if (result instanceof String) {
      String base64EncodedPng = (String) result;
      return outputType.convertFromBase64Png(base64EncodedPng);
    } else if (result instanceof byte[]) {
      String base64EncodedPng = new String((byte[]) result);
      return outputType.convertFromBase64Png(base64EncodedPng);
    } else {
      throw new RuntimeException(String.format("Unexpected result for %s command: %s",
          DriverCommand.SCREENSHOT,
          result == null ? "null" : result.getClass().getName() + " instance"));
    }
  }
  @Override
  public List<WebElement> findElements(By by) {
    return by.findElements(this);
  }
  @Override
  public WebElement findElement(By by) {
    return by.findElement(this);
  }
  protected WebElement findElement(String by, String using) {
    if (using == null) {
      throw new IllegalArgumentException("Cannot find elements when the selector is null.");
    }
    Response response = execute(DriverCommand.FIND_ELEMENT(by, using));
    Object value = response.getValue();