Added sqlite support for the insert statement

tests/sqlite/test_to_insert.cpp

@@ -0,0 +1,24 @@
+#include <gtest/gtest.h>
+
+#include <sqlgen.hpp>
+#include <sqlgen/parsing/to_insert.hpp>
+#include <sqlgen/sqlite.hpp>
+
+namespace test_to_insert {
+
+struct TestTable {
+  std::string field1;
+  int32_t field2;
+  sqlgen::PrimaryKey<uint32_t> id;
+  std::optional<std::string> nullable;
+};
+
+TEST(sqlite, test_to_insert) {
+  const auto insert_stmt = sqlgen::parsing::to_insert<TestTable>();
+  const auto conn = sqlgen::sqlite::connect().value();
+  const auto expected =
+      R"(INSERT INTO "TestTable" ("field1", "field2", "id", "nullable") VALUES (?, ?, ?, ?);)";
+
+  EXPECT_EQ(conn->to_sql(insert_stmt), expected);
+}
+}  // namespace test_to_insert