Lily Gladstone doesn’t have to speak to convey strength; we’ve seen her do remarkable things with quiet, in “Killers of the Flower Moon” and the Hulu series “Under the Bridge.” Appropriately, her character Jax in Erica Tremblay’s soulful drama “Fancy Dance” is a woman of few words; she’s a tough drifter who’s not above a little drug-dealing or petty theft (becoming less petty as the film goes on). But Jax is also a tower of strength, which Gladstone conveys through a carefully set jaw, a slightly heavy walk, a certainty to her dusk-toned voice. This woman is taking care of her 13-year-old niec…