patch 8.2.2339: cannot get the type of a value as a string

Problem:    Cannot get the type of a value as a string.
Solution:   Add typename().
diff --git a/src/testdir/test_vimscript.vim b/src/testdir/test_vimscript.vim
index dba8c73..0ba933b 100644
--- a/src/testdir/test_vimscript.vim
+++ b/src/testdir/test_vimscript.vim
@@ -6600,6 +6600,14 @@
     call ChangeYourMind()
 endfunc
 
+func Test_typename()
+  call assert_equal('number', typename(123))
+  call assert_equal('string', typename('x'))
+  call assert_equal('list<number>', typename([123]))
+  call assert_equal('dict<number>', typename(#{key: 123}))
+  call assert_equal('list<dict<number>>', typename([#{key: 123}]))
+endfunc
+
 "-------------------------------------------------------------------------------
 " Test 92:  skipping code					    {{{1
 "-------------------------------------------------------------------------------