[java][bidi]: add BiDi method `BrowsingContext.setViewport(null, null)` to reset the mobile emulation mode (#16524)

add BiDi method "BrowsingContext.setViewport(null, null, null)" for resetting mobile emulation mode

Implementation detail: according to BiDi spec (https://www.w3.org/TR/webdriver-bidi/#command-browsingContext-setViewport), we have to call method "setViewport" with "viewport" parameter equal to "null".

Co-authored-by: Diego Molina <diemol@users.noreply.github.com>