RAGFlow go API server (#13240)

# RAGFlow Go Implementation Plan 🚀

This repository tracks the progress of porting RAGFlow to Go. We'll
implement core features and provide performance comparisons between
Python and Go versions.

## Implementation Checklist

- [x] User Management APIs
- [x] Dataset Management Operations
- [x] Retrieval Test
- [x] Chat Management Operations
- [x] Infinity Go SDK

---------

Signed-off-by: Jin Hai <haijin.chn@gmail.com>
Co-authored-by: Yingfeng Zhang <yingfeng.zhang@gmail.com>

internal/cpp/stemmer/api.cpp

@@ -0,0 +1,78 @@
+// Copyright(C) 2023 InfiniFlow, Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "header.h"
+
+#include <stdlib.h> /* for calloc, free */
+
+extern struct SN_env *SN_create_env(int S_size, int I_size, int B_size) {
+    struct SN_env *z = (struct SN_env *)calloc(1, sizeof(struct SN_env));
+    if (z == NULL)
+        return NULL;
+    z->p = create_s();
+    if (z->p == NULL)
+        goto error;
+    if (S_size) {
+        int i;
+        z->S = (symbol **)calloc(S_size, sizeof(symbol *));
+        if (z->S == NULL)
+            goto error;
+
+        for (i = 0; i < S_size; i++) {
+            z->S[i] = create_s();
+            if (z->S[i] == NULL)
+                goto error;
+        }
+    }
+
+    if (I_size) {
+        z->I = (int *)calloc(I_size, sizeof(int));
+        if (z->I == NULL)
+            goto error;
+    }
+
+    if (B_size) {
+        z->B = (unsigned char *)calloc(B_size, sizeof(unsigned char));
+        if (z->B == NULL)
+            goto error;
+    }
+
+    return z;
+error:
+    SN_close_env(z, S_size);
+    return NULL;
+}
+
+extern void SN_close_env(struct SN_env *z, int S_size) {
+    if (z == NULL)
+        return;
+    if (S_size) {
+        int i;
+        for (i = 0; i < S_size; i++) {
+            lose_s(z->S[i]);
+        }
+        free(z->S);
+    }
+    free(z->I);
+    free(z->B);
+    if (z->p)
+        lose_s(z->p);
+    free(z);
+}
+
+extern int SN_set_current(struct SN_env *z, int size, const symbol *s) {
+    int err = replace_s(z, 0, z->l, size, s, NULL);
+    z->c = 0;
+    return err;
+}