HONG KONG, May 18 (Reuters Breakingviews) - Elon Musk is warming up to planting a big flag in India. Tesla is proposing to manufacture and sell vehicles in the country, Reuters reported on Wednesday, citing a source. That might make sense if the $550 billion marque becomes a market-maker, as it did in China. Musk set his satnav for India years ago. Back in 2021, the company won approval to sell its flashy cars there. Import duties of as much as 100% made it difficult to gauge demand, so Tesla lobbied to reduce tariffs, rather than producing locally. That was...