Track match index in SearchState and show it in place of match count as "X of Y".
Limit _showMatchIndex function call in findNext function only.
Verify match index in SearchState.
Make sure resultSet is empty right before updating it.
Making changes for review comments.
Merge remote-tracking branch 'origin' into rlim/show-match-index

Conflicts:
	src/search/FindReplace.js
Just check the next index for subsequent calls to update match index.
Rename `rev` with `searchBackwards`.
Merge pull request #8591 from adobe/rlim/show-match-index

Show match index in place of match count