parser-json-cov: process nested events recursively

Closes: #222

Author: kdudka

Diff for: src/lib/parser-json-cov.cc

@@ -101,6 +101,11 @@ void CovTreeDecoder::Private::readEvents(Defect *def)
         // push the event to the list of events
         DefEvent evt = covDecodeEvt(evtNode);
         def->events.push_back(std::move(evt));
+
+        // check for nested events and eventually process them recursively
+        const pt::ptree &nestedEvts = evtNode.get_child("events");
+        if (!nestedEvts.empty())
+            todo.push(nestedEvts);
     }
     while (!todo.empty());
 }

Diff for: tests/csgrep/0059-json-parser-cov-v7-cwe-stdout.txt

@@ -0,0 +1 @@
+--mode=json

Diff for: tests/csgrep/0061-json-parser-cov-v7-lang-stdout.txt

@@ -175,3 +175,4 @@ test_csgrep("0128-cov-parser-noloc"                   )
 test_csgrep("0129-sarif-gcc-pwd"                      )
 test_csgrep("0130-file-glob"                          )
 test_csgrep("0131-unicontrol-perl-man-page"           )
+test_csgrep("0132-cov-parser-nested-evt"              )