Wrap words in quotes to trigger explicit filter from query

- Do not run the more expensive explicit filter until the word to be
  filtered is completed by user. This requires an end sequence marker
  to identify end of explicit word filter to trigger filtering

- Space isn't a good enough delimiter as the explicit filter could be
  at the end of the query in which case no space

src/search_filter/explicit_filter.py

@@ -17,8 +17,8 @@ logger = logging.getLogger(__name__)
 
 class ExplicitFilter:
     # Filter Regex
-    required_regex = r'\+([^\s]+) ?'
-    blocked_regex = r'\-([^\s]+) ?'
+    required_regex = r'\+"(\w+)" ?'
+    blocked_regex = r'\-"(\w+)" ?'
 
     def __init__(self, filter_directory, search_type: SearchType, entry_key='raw'):
         self.filter_file = resolve_absolute_path(filter_directory / f"{search_type.name.lower()}_explicit_filter_entry_word_sets.pkl")