feat(check): allow using side effect imports with unknown module kinds (ex. css modules) (#23392)

This allows people to use imports like:

```ts
import "./app.css";
```

...with `deno check` in systems where there's a bundle step (ex. Vite).
This will still error when using it with `deno run` or if the referenced
file does not exist.

See test cases for behaviour.

1 files changed, 2 insertions, 0 deletions

diff --git a/tests/specs/check/css_import/exists.ts b/tests/specs/check/css_import/exists.ts
new file mode 100644
index 000000000..d5e05ae67
--- /dev/null
+++ b/tests/specs/check/css_import/exists.ts
@@ -0,0 +1,2 @@
+// should not error for deno check
+import "./app.css";