HybridWebView: Add support for C# to invoke JavaScript methods

[Eilon]

Add a few new methods to enable C# code to invoke a JavaScript method:

		/// <summary>
		/// Invokes a JavaScript method named <paramref name="methodName"/> and optionally passes in the parameter values
		/// specified by <paramref name="paramValues"/>.
		/// </summary>
		/// <param name="methodName">The name of the JavaScript method to invoke.</param>
		/// <param name="paramValues">Optional array of objects to be passed to the JavaScript method.</param>
		/// <returns>A string containing the return value of the called method.</returns>
		public async Task<string?> InvokeJavaScriptAsync(string methodName, params object[] paramValues) { ... }

		/// <summary>
		/// Invokes a JavaScript method named <paramref name="methodName"/> and optionally passes in the parameter values specified
		/// by <paramref name="paramValues"/> by JSON-encoding each one.
		/// </summary>
		/// <typeparam name="TReturnType">The type of the return value to deserialize from JSON.</typeparam>
		/// <param name="methodName">The name of the JavaScript method to invoke.</param>
		/// <param name="paramValues">Optional array of objects to be passed to the JavaScript method by JSON-encoding each one.</param>
		/// <returns>An object of type <typeparamref name="TReturnType"/> containing the return value of the called method.</returns>
		public async Task<TReturnType?> InvokeJavaScriptAsync<TReturnType>(string methodName, params object[] paramValues) { ... }

		/// <summary>
		/// Runs the JavaScript code provided in the <paramref name="script"/> parameter and returns the result as a string.
		/// </summary>
		/// <param name="script">The JavaScript code to run.</param>
		/// <returns>The return value (if any) of running the script.</returns>
		public async Task<string?> EvaluateJavaScriptAsync(string script) { ... }

[Eilon]

Fixed by #23769