## 🚀 Feature Proposal

#7753 added basic support for WebAuthn automation in the form of the `addVirtualAuthenticator` and `removeVirtualAuthenticator` methods. Implement the rest of the methods: `addCredential`, `getCredential`, `removeCredential`, `removeAllCredentials`, `setUserVerified`.

## Motivation

Support more WebAuthn use-cases, like logging in with a specific credential, handling user verification failures, and inspecting generated credentials.

## Example

For a page like this

```html
<button id="login">Log in with WebAuthn</button>
<span id="result"></span>
```

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

A test could be written like so:

```java
// Set up the virtual authenticator.
HasVirtualAuthenticator virtualAuthenticatorManager = ((HasVirtualAuthenticator) driver);
VirtualAuthenticatorOptions options = new VirtualAuthenticatorOptions();
VirtualAuthenticator authenticator =
    virtualAuthenticatorManager.addVirtualAuthenticator(options);

// New code: inject a credential into the authenticator.
// Without this API the developer would have to generate a credential through
// navigator.credentials.create({...}) on the javascript side and would have less
// control over the resulting PK.
Credential credential = Credential.createNonResidentCredential(...params);
virtualAuthenticatorManager.addCredential(authenticator, credential);

// Assert login successful:
driver.findElement(By.id("login")).click();
WebElement result = driver.findElement(By.id("result"));
new WebDriverWait(driver, 60, 1000).until(
    driver -> !result.getText().equals(""));
assertThat(result.getText()).isEqualTo("Success!");
```
import static org.openqa.selenium.remote.DriverCommand.STATUS;
import static org.openqa.selenium.remote.DriverCommand.SWITCH_TO_CONTEXT;
import static org.openqa.selenium.remote.DriverCommand.SWITCH_TO_FRAME;
import static org.openqa.selenium.remote.DriverCommand.SWITCH_TO_NEW_WINDOW;
import static org.openqa.selenium.remote.DriverCommand.SWITCH_TO_PARENT_FRAME;
import static org.openqa.selenium.remote.DriverCommand.SWITCH_TO_WINDOW;
import static org.openqa.selenium.remote.DriverCommand.UPLOAD_FILE;
import static org.openqa.selenium.remote.http.Contents.bytes;
import static org.openqa.selenium.remote.http.Contents.string;
import com.google.common.base.Objects;
import com.google.common.base.Splitter;
import com.google.common.base.Strings;
import com.google.common.collect.ImmutableList;
import org.openqa.selenium.UnsupportedCommandException;
import org.openqa.selenium.json.Json;
import org.openqa.selenium.net.Urls;
import org.openqa.selenium.remote.Command;
import org.openqa.selenium.remote.CommandCodec;
import org.openqa.selenium.remote.SessionId;
import org.openqa.selenium.remote.http.HttpMethod;
import org.openqa.selenium.remote.http.HttpRequest;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
/**
 * A command codec that adheres to the W3C's WebDriver wire protocol.
 *
 * @see <a href="https:w3.org/tr/webdriver">W3C WebDriver spec</a>
 */
public abstract class AbstractHttpCommandCodec implements CommandCodec<HttpRequest> {