refactor: split formatters and matchers into separated singleton classes (#166)

* split formatter into separated singleton classes

* split data engine matchers to classes

* nodiscard attribute for formatter methods

* small refactoring in matchers

* fix codefactor warnings

* fix test building

sources/awesome-widget/plugin/awpatternfunctions.h

@@ -23,7 +23,7 @@
 
 class AWKeysAggregator;
 
-namespace AWPatternFunctions
+namespace __attribute__((visibility("default"))) AWPatternFunctions
 {
 typedef struct {
     QStringList args;