fix(fuselage): explicit Grid breakpoint props don't apply container gutters #42809

Description

Grid puts its explicit breakpoint class (rcx-grid--{bp}) on the same element as rcx-grid, but the gutter mixin in Grid.styles.scss only matches .rcx-grid--{bp} > .rcx-grid. The items get that breakpoint's padding, but the container keeps the media-query breakpoint's negative margins, so the gutters don't line up.

Suggested fix

Also match &.rcx-grid--{bp} on the same element.

Context

Found by cubic while reviewing #42763, which moved @rocket.chat/fuselage into this monorepo. The behavior is unchanged from Fuselage 0.96.0, so it was out of scope there.