Speaker of the House Mike Johnson is seen at the Capitol on April 11. Chip Somodevilla/Getty ImagesHouse Speaker Mike Johnson is making an effort to emphasize close ties to former President Donald Trump as the Louisiana Republican faces the threat of a vote to strip him of the speaker’s gavel.Johnson and Trump will appear together at Mar-a-Lago on Friday to deliver joint remarks and make an announcement on “election integrity.” The event, which sources say was the speaker’s idea, comes as Johnson confronts the most serious challenge to his speakership to date, as GOP Rep….