Front end test 6.2.x

By the documentation that we originally used to develop themes, there should only be 1 css file for all the custom code. [(See this page)](https://www.liferay.com/documentation/liferay-portal/6.2/development/-/ai/creating-liferay-themes-liferay-portal-6-2-dev-guide-09-en)  However, I left the files intact because I noticed that the classic theme has the same css file structure. If you wanted to combine them, you could put them in one file with custom_responsive.css first, then custom_common.css, and lastly custom.css. This is the order they are currently read in (based on the @include commands), so the rules would cascade in the same way. (I did not see main_rtl.css referenced anywhere, so I am not sure where to include that).

Similarly, the color schemes do not use a common.css file by the documentation. In the interest of preventing duplicate code, I left the files as is, but it would be possible to paste the contents of that file into the beginning of dark.css and light.css and have the same affect.

For the link to the Liferay site, I tried to leverage an existing function, openIn Dialog. The function openWindow is defined in portlet.js and is then used to define openInDialog in util.js.

For the sign in dialog, I tried to use the modal alloy ui component, but it is not currently working.