Shirley Ju Kendrick Lamar’s fifth studio album, “Mr. Morale & the Big Steppers,” is already the biggest first-week debut of 2022. With its arrival comes 18 tracks of introspection touching on everything from racism to transphobia to generational trauma.One of those tracks, “Purple Hearts” featuring R&B queen Summer Walker and Wu-Tang Clan alum Ghostface Killah, came to life with the help of Westside Boogie, the Shady Records signee who co-wrote it.