Add CI workflow to check line endings of all source files (#2082)

In addition, all found errors (formatting & line ending) have been fixed in this PR.

src/common/Credentials.hpp

@@ -1,23 +1,23 @@
-#pragma once
-
-#include <QString>
-#include <functional>
-
-namespace chatterino {
-
-class Credentials
-{
-public:
-    static Credentials &instance();
-
-    void get(const QString &provider, const QString &name, QObject *receiver,
-             std::function<void(const QString &)> &&onLoaded);
-    void set(const QString &provider, const QString &name,
-             const QString &credential);
-    void erase(const QString &provider, const QString &name);
-
-private:
-    Credentials();
-};
-
-}  // namespace chatterino
+#pragma once
+
+#include <QString>
+#include <functional>
+
+namespace chatterino {
+
+class Credentials
+{
+public:
+    static Credentials &instance();
+
+    void get(const QString &provider, const QString &name, QObject *receiver,
+             std::function<void(const QString &)> &&onLoaded);
+    void set(const QString &provider, const QString &name,
+             const QString &credential);
+    void erase(const QString &provider, const QString &name);
+
+private:
+    Credentials();
+};
+
+}  // namespace chatterino