SDC stylesheets should be added in the "theme" aggregate group (as opposed to "default" group) to correct CSS source order

Source order of the CSS matters, and it's important that we get this correct. Currently all SDC CSS is added into a “default” aggregate group. The net effect of this is that SDC CSS gets lumped in with core module CSS, and gets injected before any base theme styles.

Current behavior

• SDC CSS's tag will get injected into the HTML before any library CSS (including the base group). I expect this to be injected after any dependencies or any base group CSS
• If I set a dependency on a SDC to a library, the library's CSS is still loaded after the component.

Expectation

• SDC CSS should be loaded after the base and layout CSS defined within the active theme.

Steps to reproduce

Enable SDC, create an SDC component in your default base theme. Create and include SDC component. Create a library with CSS with a base weight. Observe the SDC component.css rendering prior to the theme's reset.css.