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.

10 files changed, 44 insertions, 0 deletions

diff --git a/tests/specs/check/css_import/__test__.jsonc b/tests/specs/check/css_import/__test__.jsonc
new file mode 100644
index 000000000..629dcd383
--- /dev/null
+++ b/tests/specs/check/css_import/__test__.jsonc
@@ -0,0 +1,24 @@
+{
+  "steps": [{
+    "args": "check exists.ts",
+    "output": "exists.out"
+  }, {
+    "args": "run --check exists.ts",
+    "output": "exists_run_with_check.out",
+    "exitCode": 1
+  }, {
+    "args": "check not_exists.ts",
+    "output": "not_exists.out",
+    "exitCode": 1
+  }, {
+    "args": "check exists_and_try_uses.ts",
+    "output": "exists_and_try_uses.out",
+    "exitCode": 1
+  }, {
+    "args": "check exists_dynamic_import.ts",
+    "output": "Check file:///[WILDCARD]exists_dynamic_import.ts\n"
+  }, {
+    "args": "run --check --reload exists_dynamic_import.ts",
+    "output": "Check file:///[WILDCARD]exists_dynamic_import.ts\n"
+  }]
+}
diff --git a/tests/specs/check/css_import/app.css b/tests/specs/check/css_import/app.css
new file mode 100644
index 000000000..e69de29bb
--- /dev/null
+++ b/tests/specs/check/css_import/app.css
diff --git a/tests/specs/check/css_import/exists.out b/tests/specs/check/css_import/exists.out
new file mode 100644
index 000000000..1e9af3607
--- /dev/null
+++ b/tests/specs/check/css_import/exists.out
@@ -0,0 +1 @@
+Check [WILDLINE]exists.ts
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";
diff --git a/tests/specs/check/css_import/exists_and_try_uses.out b/tests/specs/check/css_import/exists_and_try_uses.out
new file mode 100644
index 000000000..b51ea2391
--- /dev/null
+++ b/tests/specs/check/css_import/exists_and_try_uses.out
@@ -0,0 +1,5 @@
+Check file:///[WILDLINE]/exists_and_try_uses.ts
+error: TS1192 [ERROR]: Module '"file:///[WILDLINE]/app.css"' has no default export.
+import test from "./app.css";
+       ~~~~
+    at file:///[WILDLINE]/exists_and_try_uses.ts:1:8
diff --git a/tests/specs/check/css_import/exists_and_try_uses.ts b/tests/specs/check/css_import/exists_and_try_uses.ts
new file mode 100644
index 000000000..afaa6e4e0
--- /dev/null
+++ b/tests/specs/check/css_import/exists_and_try_uses.ts
@@ -0,0 +1,3 @@
+import test from "./app.css";
+
+test(123);
diff --git a/tests/specs/check/css_import/exists_dynamic_import.ts b/tests/specs/check/css_import/exists_dynamic_import.ts
new file mode 100644
index 000000000..14f63fd23
--- /dev/null
+++ b/tests/specs/check/css_import/exists_dynamic_import.ts
@@ -0,0 +1,3 @@
+if (false) {
+  await import("./app.css");
+}
diff --git a/tests/specs/check/css_import/exists_run_with_check.out b/tests/specs/check/css_import/exists_run_with_check.out
new file mode 100644
index 000000000..1a1dafeb7
--- /dev/null
+++ b/tests/specs/check/css_import/exists_run_with_check.out
@@ -0,0 +1,3 @@
+error: Expected a JavaScript or TypeScript module, but identified a Unknown module. Importing these types of modules is currently not supported.
+  Specifier: file:///[WILDLINE]/app.css
+    at file:///[WILDLINE]/exists.ts:2:8
diff --git a/tests/specs/check/css_import/not_exists.out b/tests/specs/check/css_import/not_exists.out
new file mode 100644
index 000000000..95fd14668
--- /dev/null
+++ b/tests/specs/check/css_import/not_exists.out
@@ -0,0 +1,2 @@
+error: Module not found "file:///[WILDLINE]/not_exists.css".
+    at file:///[WILDLINE]/not_exists.ts:1:8
diff --git a/tests/specs/check/css_import/not_exists.ts b/tests/specs/check/css_import/not_exists.ts
new file mode 100644
index 000000000..762c9acd7
--- /dev/null
+++ b/tests/specs/check/css_import/not_exists.ts
@@ -0,0 +1 @@
+import "./not_exists.css";