Add simple search functionality

[Kaliumhexacyanoferrat]

As a developer of a web application, I would like to plug in a search page into my content so that my users can search for content and I do not need to implement it by myself.

Example

var content = Layout.Create()
                    .Add("search", Search.Create());

var app = Website.Create()
                 .Content(content);             

Acceptance criteria

• The search handler provides a web UI that allows to search for a given query and is able to show search results (with navigation)
• The functionality is provided in a new module (GenHTTP.Modules.Search)
• The UI of the search can be adjusted via CSS as needed (all items have ids/classes)
• Developers may directly open the search result page (e.g. pass query via GET / POST)
• Search results are not indexed in search engines
• The functionality is documented on the website