[Look&Feel] All pages should have padding left and right paddingSize="m" (default)

[ruanyl]

This is a UX request that all pages should have aligned padding left and right size, this sounds a good candidate for look & feel project.

@AMoo-Miki @virajsanghvi

[AMoo-Miki]

Page content should have 16px padding wrt to the application container. The inner content should not add any paddings or margins that impact their spacing from that container.