## 🚀 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!");
```
* @param method The HTTP method to use for the command.
   * @param pathPattern The URI path pattern for the command. When encoding a command, each
   *     path segment prefixed with a ":" will be replaced with the corresponding parameter
   *     from the encoded command.
   */
  @Override
  public void defineCommand(String name, HttpMethod method, String pathPattern) {
    defineCommand(name, new CommandSpec(method, pathPattern));
  }
  @Override
  public void alias(String commandName, String isAnAliasFor) {
    aliases.put(commandName, isAnAliasFor);
  }
  protected void defineCommand(String name, CommandSpec spec) {
    checkNotNull(name, "null name");
    nameToSpec.put(name, spec);
  }
  protected static CommandSpec delete(String path) {
    return new CommandSpec(HttpMethod.DELETE, path);
  }
  protected static CommandSpec get(String path) {
    return new CommandSpec(HttpMethod.GET, path);
  }
  protected static CommandSpec post(String path) {
    return new CommandSpec(HttpMethod.POST, path);
  }
  private String buildUri(
    String commandName,
    SessionId sessionId,
    Map<String, ?> parameters,