Add search and pagination to the CM sitemap listing

User story

As a content editor, I would love to be able to search for sitemap items, and also use pagination to find my way through them, as our channels contain hundreds of pages and finding the specific one I want can be really really difficult in one huge list.

Acceptance Criteria

Please scan through all of the attached images before reading the below acceptance criteria

A) Pagination is present at the bottom of the sitemap listing

• user can change the number of items contained in one page using a dropdown. Default selected = 20.
• offers users the ability to move forward and back one page at a time
• offers users the ability to jump to the very first page and to also jump to the very last page 
• is based on either the full listing or the modified listing of sitemap items based on the user executing a search
• scroll independent (where the user has scrolled to has no impact on the pagination items)
• the arrows available for a user to use are dependent on their current page position. E.g. if they are on the last page there are no forward arrows

B) Search functionality is added to the top of the sitemap listing in the channel manager

• 'X' appears once a user starts to type; clicking it will clear a search
• Placeholder text = Search
• The sitemap listing starts being automatically refined once a user starts typing
• Autocomplete functionality also exists- a maximum of 4 items can be suggested. The autocomplete box does not hide/overlap with any of the listed items and instead pushes them down
• A search is executed when the user either:

– presses enter
– selects an autocomplete suggestion

On executing a search the sitemap list updates with the relevant items and the first item in the list is given a hover-state.

*NOTE: Search bar design and functionality should be the same as implemented for https://issues.onehippo.com/browse/PM-28*

C) Users can navigate through the sitemap listing at any time by using the tab-button or arrow-buttons (or by scrolling with a mousepad of course)