By Leika Kihara TOKYO, July 1 (Reuters) – Big Japanese manufacturers’ sentiment improved in the three months to June to levels unseen since 2018, a closely watched survey showed on Wednesday, a sign the economy was weathering the energy shock from the Middle East conflict for now. The headline index measuring big manufacturers’ business sentiment stood at +22 in June, up from +17 in March and exceeded a median market forecast for a readin…