Only suppress warnings in Vite dev mode and on client

[myieye]

We can't use this package unless this fix gets merged.

As I commented, suppressWarnings currently kills our node server, which is pretty wild, because it only gets "uninstrumented" on the client, so the console.warn call stack just grows and grows.

This is an improvement to the currently open PR #63.

The warnings are only logged in dev mode, so we can leave console.warn alone if we know that we're not in dev mode.
And we certainly don't want to touch globals in node/on the server.

I did my best to determine dev mode and client without assuming we're running in a Vite app.
If the code is not running in a Vite app, then we can't detect dev mode, so it will behave the same in the browser as it did before.
Except that I made the filter a bit smarter, so that it should only suppress warnings that are actually caused by markdown renderers.

[jstjoe]

@pablo-abc thank you for approving this but it looks like it still needs to be merged? Could you do that, or add someone else as maintainer? 🙏