Address all code review items from #7705 except for showError()/showNoResults() and parseQuery() cleanup
Lots of small code review cleanups from #7809:
* Got rid of unnecessary partial in search-summary-paging.html
* Refactored change notifications in Document to _notifyDocumentChange() method, and fix up similar logic in SpecRunnerUtils.createMockActiveDocument()
* Moved makeDialogFileList from StringUtils to FileUtils
* Renamed "file/item/index" to "fileIndex/itemIndex/matchIndex" for clarity in SearchResultsView
* Return empty array from _getSearchMatches instead of null
* Properly debounce document changes when updating search results view
* Fix up file rename handling in search results view to use indexOf() instead of match()
* Rename "doReplaceAll" event on FindBar to "replaceAll"
* Return a promise from FindInFilesUI.searchAndShowResults()
* Replace calls to _.filter() and _.map() with native JS calls
* Lots of comment/JSDoc improvements
Move special-case handling of multifile Replace All UI interactions into FindBar
Make SearchModel keep an accurate count of results without recounting every time

Also fixes a long-standing bug in updating line numbers for existing result matches.
Fix up File Filters unit tests to work with FindInFiles refactoring. Clean up duplicate code.
More code review fixes:

* Got rid of "navigator" and "scope" options to FindBar, since they're redundant with "multifile"
* Renamed SearchModel.addResults() to setResults() and made it remove the existing results first if any
* Comment clarifications
Final code cleanups/fixes for replace in files
Always clear results for previous search even if there are no new matches
Nicer fix for always clearing old search results
Merge pull request #8137 from adobe/nj/replace-review-fixes

[replace-across-files] Code review fixes