THE ALL ENGLAND CLUB, London — At 32 years old, Jessica Pegula has figured something out about playing on grass, tennis’s most specialized surface that happens to host its most important Grand Slam. She’s learned that it’s not about slicing every ball that comes her way or moving into net more than she’d like. She can do both of those things, as a clean hitter who spent a fair share of her career on the doubles court, but in years past, she’d been forcing herself to empty the toolbox simply beca