Regex metacharacters result in error post search

After receiving search results, the user query was used to sort and
highlight results. If a part of the search included an incomplete regex
syntax (such as a regex metacharacter) it fails to compile the pattern.

Repro steps:
1) Create file with regex metacharactes in name Example: "(test).txt"
2) Search for file using partial name, and only single regex character
(from a set such as "()" or "[]"). Example: "("

Expected results:
Search shows correct files

Observed results:
Search ends up crashing FileManager

Change-Id: Idf5ee3b441481574a5bada1ca7e9048109a13435
Ticket: QRDL-1035