refactor(exceptions): made header names consistent

All header names in the exceptions module now follow the same naming
scheme.

src/include/gridfire/exceptions/error_gridfire.h

@@ -0,0 +1,17 @@
+#pragma once
+#include <exception>
+
+#include <string>
+
+namespace gridfire::exceptions {
+    class GridFireError : public std::exception {
+    public:
+        explicit GridFireError(std::string msg) : m_msg(std::move(msg)) {}
+
+        [[nodiscard]] const char* what() const noexcept override {
+            return m_msg.c_str();
+        }
+    private:
+        std::string m_msg;
+    };
+}