Add icon, iconPosition and showIcon support in DataSearch and CategorySearch

[divyanshu013]

Resolved via https://github.com/appbaseio/reactivesearch/commit/b68de12a8a17424c30ba2f88c01b0edd0e7b9433 https://github.com/appbaseio/reactivesearch/commit/f3e0e21fe8c2e4a1f597f295d7a8ea68c1947b8c https://github.com/appbaseio/reactivesearch/commit/6f9195b4018932a074e66048cba9aa803383f266 https://github.com/appbaseio/reactivesearch/commit/79cab45a8c94a10a439bb12f8751eab6e87316ec https://github.com/appbaseio/reactivesearch/commit/56b2ad2ab4736290a258d338daeb016174112013 https://github.com/appbaseio/reactivesearch/commit/ce84cc94165f709b3889cf8cfdc6fcc5bc7464a9