feat: embed analytics

If cookies are accepted, the script will look at window.analyticsConfig and build the needed vendor scripts for the specified services.

This works for:

• Umami
• Counter.dev
• GTM

For Hugo sites, the analyticsConfig will be created via a partial which reads analytics-related params in config.toml. E.g. It will grab the GTM ID and insert it into analyticsConfig.

This can also work with non-Hugo sites, but they will need to fill out their own window.analyticsConfig.