Skip exclusions completely instead of adding them temporarily

...to the source path. The rationale for this is that language features
would be provided even for excluded files, e.g. .kts scripts when
`kotlin.scripts.enabled` is disabled or source files in auto-generated
directories such as `./bin`.

server/src/main/kotlin/org/javacs/kt/SourceFiles.kt

@@ -74,8 +74,10 @@ class SourceFiles(
     private val open = mutableSetOf<URI>()
 
     fun open(uri: URI, content: String, version: Int) {
-        files[uri] = SourceVersion(content, version, languageOf(uri), isTemporary = !exclusions.isURIIncluded(uri))
-        open.add(uri)
+        if (exclusions.isURIIncluded(uri)) {
+            files[uri] = SourceVersion(content, version, languageOf(uri), isTemporary = false)
+            open.add(uri)
+        }
     }
 
     fun close(uri: URI) {