Insert `dsn: process.env.NEXT_PUBLIC_SENTRY_DSN || 'actualdsn'` instead of just the dsn

[lforst]

That makes it a) easier to configure the DSN b) easier for people to understand how to parameterize the DSN properly.

[lforst]

When I sat down and implemented this, I realized this might be a really bad idea.

So basically we would be adding

dsn: process.env.NEXT_PUBLIC_SENTRY_DSN || "${dsn}"

That makes it very easy for people to configure the DSN via an env var, however, when they had NEXT_PUBLIC_SENTRY_DSN previously set to something other than the dsn that was inserted, they are gonna have a VERY bad time because their events won't show up where they would expect them to.

Gonna put this off.