Allow for passing a script name and parameter from the host page through the iframe url.

[fuzzzerd]

Update load event to check current page query string and update generated uri to include the FileMaker script and parameter variables.

See also:

• WebDLanding/src/WebDLanding/wwwroot/webdlanding.js

  Lines 36 to 41 in 1d4e58e

  	window.addEventListener("load", function () {
  	if (homeUri) {
  	uri = uri + "?homeurl=" + homeUri + "/logoff.html";
  	}
  	document.getElementById("webdirect-frame").src = uri;
  	});

• https://fmhelp.filemaker.com/docs/16/en/fmwd/index.html#accessing_linking

?script=name-of-script&param=script-param

Need to validate that all optional parameters work correctly in any combination and produces a valid uri.