[feature] Issue: #45 Support for INVISIBLE indexes

This feature is ported from upstream 8.0.

As 8.0 introduces Data Dictionary which substitute metadata files

in server layer used in previous version(such as frm) , so there are

some subtle differences.

1. we store index visibility info in frm

2. we use the HA_SORT_ALLOWS_SAME flag, which was not stored in frm

   before, in frm to indicate HA_INVISIBLE_KEY, so that we don't need

   to expand frm format, and compatibility is held.

 Description

  ============

  bug#88847, this issue is related to invisible indexes feature which we ported

  from 8.0 upstream. Invisible index is not considered by slave SQL row applier

  when searching index to use, and choosed anyway as long as the index is fit for

  update.

  Solution:

  ============

  Make slave SQL applier thread respecting invisible indexes and don't choose them

  when searching index to use.