Split out some pieces of this component

[ctrueden]

Right now, this component contains the following:

1. Core search framework: SearchService and Searcher plugin type.
2. Searcher plugin implementation for modules
3. Searcher plugin implementations for online resources including BISE, ImageJ wiki and ImageJ forum
4. Swing UI search bar for use in Swing-oriented UIs

(1) belongs here for sure. (2) is debatable, but isn't a serious problem living here for now. (3) is ImageJ-centric and belongs elsewhere, probably in imagej/imagej-plugins-search. (4) is Swing-specific and belongs elsewhere, probably in scijava/scijava-ui-swing.