Enabled search inside hidden directories

[gave92]

Fir #2447

This PR:

• handles errors that can be thrown by StorageFolder.GetFolderFromPathAsync()
• allows to search inside hidden folders (shallow search only)
• fix a bug for which returned hidden items were not filtered by search term
• fix a bug for which results were ordered by file name instead of search rank
• return at most *maxItemsCount` results
• small code refactor

[yaira2]

fix a bug for which results are ordered by file name instead of search rank

@gave92 This was done intentionally so that the most relevant items would show on the quick search drop down. Is there a way to have the drop-down sort by name and have the search results page sort by rank?

[gave92]

@yaichenbaum mmm I'm not getting the most relevant results atm.

Example search:
I'm looking for files named "test". If in the current path I have a folder also named "test" in the dropdown I get all the files contained inside the "test" folder. Instead I'd like to see files matching "test" first.

Doesn't sorting by rank guarantee that I get the most relevant results?
If they are sorted by filename I get a lot of uninteresting stuff instead

[yaira2]

@gave92 Great work!