IDE test: add missing stripMargin for code interpolator

This means that many tests were failing to compile previously, but we
never noticed.

FIXME: Somehow, this broke the documentation test in
HoverTest (the @usecase part of the doc is missing from the output now)

Author: smarter

language-server/test/dotty/tools/languageserver/SymbolTest.scala

@@ -21,11 +21,11 @@ class SymbolTest {
       code"class $Bar",
       code"""package foo
             |class $fooFoo {
-            |  class Bar
+            |  class ${m7}Bar$m8
             |}
           """
     ) .symbol("Foo", Foo.range.symInfo("Foo", SymbolKind.Class), fooFoo.range.symInfo("Foo", SymbolKind.Class, "foo"))
-      .symbol("Bar", Bar.range.symInfo("Bar", SymbolKind.Class))
+      .symbol("Bar", Bar.range.symInfo("Bar", SymbolKind.Class), (m7 to m8).symInfo("Bar", SymbolKind.Class, "Foo"))
   }
 
   @Test def symbolShowModule: Unit = {

language-server/test/dotty/tools/languageserver/util/Code.scala

@@ -106,7 +106,7 @@ object Code {
       }
 
       if (pi.hasNext)
-        stringBuilder.append(pi.next())
+        stringBuilder.append(pi.next().stripMargin)
 
       (stringBuilder.result(), positions.result())
     }