completions: do not complete package

There is an issue with completions for package in Metals.

```scala
// code
package one@@
// compeltions
oneCURSOR
```

It seems there is no need in completions for Package at all.

Author: dos65

Diff for: compiler/src/dotty/tools/dotc/interactive/Completion.scala

@@ -211,6 +211,8 @@ object Completion:
     val completer = new Completer(mode, pos, untpdPath, matches0)
 
     val result = adjustedPath match
+      // Ignore `package foo@@` and `package foo.bar@@`
+      case ((_: tpd.Select) | (_: tpd.Ident)):: (_ : tpd.PackageDef) :: _       => Map.empty
       // Ignore synthetic select from `This` because in code it was `Ident`
       // See example in dotty.tools.languageserver.CompletionTest.syntheticThis
       case tpd.Select(qual @ tpd.This(_), _) :: _ if qual.span.isSynthetic      => completer.scopeCompletions

Diff for: presentation-compiler/test/dotty/tools/pc/tests/completion/CompletionSuite.scala

@@ -1952,3 +1952,17 @@ class CompletionSuite extends BaseCompletionSuite:
       """TestEnum test
         |""".stripMargin,
     )
+
+  @Test def `packageIssueIdent` =
+    check(
+      """package one@@
+        |""".stripMargin,
+      ""
+    )
+  
+  @Test def `packageIssueSelect` =
+    check(
+      """package one.two@@
+        |""".stripMargin,
+      ""
+    )