Perform an interactive search.
ENGINE is the Xesam search engine to be applied, it must be one of the
entries of `xesam-search-engines'. QUERY is the search string in the
Xesam user query language. If the search engine does not support
the Xesam user query language, a Xesam fulltext search is applied.
The default search engine is the first entry in `xesam-search-engines'.
Example:
(xesam-search (car (xesam-search-engines)) "emacs")
(fn ENGINE QUERY)