Rihanna has touched down in Gujrat, India, ahead of what will surely be one of the largest events of the new year: the pre-wedding celebration of billionaire heir Anant Ambani. Ambani is set to exchange vows with fiancée Radhika Merchant this July but is kicking off the festivities early with a three-day extravaganza in Jamnagar, RadarOnline.com has learned. RiRi will treat attendees to a rare performance of her biggest hits, according to reports. Punjabi music star Diljit Dosanjh and magician David Blaine will also be taking the stage to wow the crowd. On Thursday, the Barbadian beauty was se…