patch 9.0.1785: wrong cursor position with 'showbreak' and lcs-eol

Problem:  wrong cursor position with 'showbreak' and lcs-eol
Solution: Add size of 'showbreak' before when 'listchars' "eol" is used.
          Also fix wrong cursor position with wrapping virtual text on
          empty line and 'showbreak'.

closes: #12891

Signed-off-by: Christian Brabandt <cb@256bit.org>
Co-authored-by: zeertzjq <zeertzjq@outlook.com>
diff --git a/src/testdir/test_textprop.vim b/src/testdir/test_textprop.vim
index c272f2e..05bba61 100644
--- a/src/testdir/test_textprop.vim
+++ b/src/testdir/test_textprop.vim
@@ -2687,6 +2687,8 @@
   call VerifyScreenDump(buf, 'Test_prop_inserts_text_showbreak_20', {})
   call term_sendkeys(buf, "\<C-E>")
   call VerifyScreenDump(buf, 'Test_prop_inserts_text_showbreak_21', {})
+  call term_sendkeys(buf, "zbx")
+  call VerifyScreenDump(buf, 'Test_prop_inserts_text_showbreak_22', {})
 
   call StopVimInTerminal(buf)
 endfunc