By Asif Shahzad and Mubasher Bukhari WAZIRABAD, Pakistan (Reuters) -Former Pakistani Prime Minister Imran Khan said on Friday he would resume his protest march to Islamabad after recovering from an assassination attempt, as his supporters staged nationwide protests that blocked major roads. Khan was shot in the leg on Thursday as he waved to crowds from a container mounted on a truck from where he was leading a protest march on the capital to press for early elections and calling for the resignation of Prime Minister Shehbaz Sharif. Sharif led a coalition of parties that ousted Khan from offic…