patch 8.2.3413: Vim9: too many characters are allowed in import name

Problem:    Vim9: too many characters are allowed in import name.
Solution:   Disallow ':' and '#', check for white space. (closes #8845)
diff --git a/src/testdir/test_vim9_script.vim b/src/testdir/test_vim9_script.vim
index 2600bbd..313bfbc 100644
--- a/src/testdir/test_vim9_script.vim
+++ b/src/testdir/test_vim9_script.vim
@@ -1490,6 +1490,23 @@
       var that = foo
   END
   CheckScriptFailure(lines, 'E1029: Expected ''.''')
+
+  lines =<< trim END
+      vim9script
+      import * as 9foo from './Xfoo.vim'
+  END
+  CheckScriptFailure(lines, 'E1047:')
+  lines =<< trim END
+      vim9script
+      import * as the#foo from './Xfoo.vim'
+  END
+  CheckScriptFailure(lines, 'E1047:')
+  lines =<< trim END
+      vim9script
+      import * as g:foo from './Xfoo.vim'
+  END
+  CheckScriptFailure(lines, 'E1047:')
+
   delete('Xfoo.vim')
 enddef