Support discriminating between protocol support for endpoints

[tristanlabelle]

Some endpoints will support the WebDriver protocol and others the Selenium legacy JSON protocol. WebDriver instances should be able to report which one of these they support, so that Session and Element can have conditional logic where needed.

public enum WireProtocol {
    /// The Selenium legacy wire protocol,
    /// as described at https://www.selenium.dev/documentation/legacy/json_wire_protocol
    case SeleniumLegacy
    /// The W3C-standard WebDriver protocol,
    /// as described at https://www.w3.org/TR/webdriver1 & https://www.w3.org/TR/webdriver2
    case W3CWebDriver(version: Int)
}