webui: add quick search to Configuration/DVB Inputs/Services tab

This commit adds a text field titled "Search service name..." to the Services tab. Any text entered will filter the set of displayed services.

I have about 2700 services in this view and I would like to hand-pick about 50 of them to map them to channels. This quick search bar makes it a lot easier to find the services I want to map quickly.

I am not sure if my way of injecting the filter is the correct way. However, it seems to work okay.
I don't think that it's good implementation. I would prefer to set the value in the grid filter (click to column header on V menu and you may set a filter for this column).