RSC: Silence unsupported-dynamic-import warning

[Tobbe]

We were getting a bunch of warnings like these

● [DEBUG] This "import" expression will not be bundled because the argument is not a string literal [unsupported-dynamic-import]

    assets/Routes-!~{00n}~.mjs:12137:18:
      12137 │     return (await import(rdServerPath)).default;

Adding /* @vite-ignore */ doesn't help, because this is an esbuild warning.

There are a lot of issues on the esbuild repo about this warning. evanw/esbuild#1155 is one, and it also lists a whole bunch of others.
Here's an open issue about adding support for comments, like the vite one I've already tried with, for esbuild: evanw/esbuild#1240. When/if that issue gets resolved we should move to using that. For now I'm silencing all "unsupported-dynamic-import" warnings, which isn't ideal, but will have to do for now.
Here's a vite issue about silencing an esbuild warning vitejs/vite#14768, and the answer there is to use esbuild.logLevel, which is what I also do in this PR