Adding support for isGenerator tasks

- Changing how DAG is represented, both in code and how DAGs are defined
  in JSON.
- Removing std::vector<Task> representation in favour of a map that will
  enforce unique task names
- Task names now have a name (generated), and a definedName.
- Adding support to loggers to add tasks after a DAGRun has been
  initialized.

tests/unit_dagrun_loggers.cpp

@@ -0,0 +1,67 @@
+#include <iostream>
+#include <filesystem>
+#include <fstream>
+
+#include <catch2/catch.hpp>
+
+#include "daggy/loggers/dag_run/FileSystemLogger.hpp"
+#include "daggy/loggers/dag_run/OStreamLogger.hpp"
+
+namespace fs = std::filesystem;
+
+using namespace daggy;
+using namespace daggy::loggers::dag_run;
+
+const TaskList SAMPLE_TASKS{
+        {"work_a", Task{.command{"/bin/echo", "a"}, .children{"c"}}},
+        {"work_b", Task{.command{"/bin/echo", "b"}, .children{"c"}}},
+        {"work_c", Task{.command{"/bin/echo", "c"}}}
+};
+
+inline DAGRunID testDAGRunInit(DAGRunLogger &logger, const std::string &name, const TaskList &tasks) {
+    auto runID = logger.startDAGRun(name, tasks);
+    auto dagRun = logger.getDAGRun(runID);
+
+    REQUIRE(dagRun.tasks == tasks);
+
+    REQUIRE(dagRun.taskRunStates.size() == tasks.size());
+    auto nonQueuedTask = std::find_if(dagRun.taskRunStates.begin(), dagRun.taskRunStates.end(),
+                                      [](const auto &a) { return a.second != +RunState::QUEUED; });
+    REQUIRE(nonQueuedTask == dagRun.taskRunStates.end());
+
+    REQUIRE(dagRun.dagStateChanges.size() == 1);
+    REQUIRE(dagRun.dagStateChanges.back().newState == +RunState::QUEUED);
+    return runID;
+}
+
+/*
+TEST_CASE("Filesystem Logger", "[filesystem_logger]") {
+    const fs::path logRoot{"fs_logger_unit"};
+    auto cleanup = [&]() {
+        if (fs::exists(logRoot)) {
+            fs::remove_all(logRoot);
+        }
+    };
+
+    //cleanup();
+    daggy::loggers::dag_run::FileSystemLogger logger(logRoot);
+
+    SECTION("DAGRun Starts") {
+        testDAGRunInit(logger, "init_test", SAMPLE_TASKS);
+    }
+
+    // cleanup();
+}
+*/
+
+TEST_CASE("ostream Logger", "[ostream_logger]") {
+    //cleanup();
+    std::stringstream ss;
+    daggy::loggers::dag_run::OStreamLogger logger(ss);
+
+    SECTION("DAGRun Starts") {
+        testDAGRunInit(logger, "init_test", SAMPLE_TASKS);
+    }
+
+    // cleanup();
+}