Page layout API edits and small design rinse

[jxnblk]

This is a PR for discussion about the page layout API and to demonstrate some potential areas for improvement.

• Removes styling from the src/pages template, leaving that component to be primarily responsible for the GraphQL query and not something that is likely to be shadowed
• Moves the Head component call to the Layout component + passes the page props through to the Layout component
• The shadow Layout component now includes the Head component; this could potentially make it easy to include additional elements in the head from the site's layout component
• Adds a Page component to handle the base-level styles
• Removes CSS Modules composes calls that relied on other CSS files (currently this seems potentially confusing with shadowing)
• Updates the starters Layout component styles (just for aesthetic reasons)

This is by no means perfect, but let me know what you think

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[jxnblk]

Awesome, I'll take another pass to make sure I didn't creating any styling regressions after merging the latest from main in