Feat: add splitter (#10161)

### What problem does this PR solve?


### Type of change
- [x] New Feature (non-breaking change which adds functionality)

---------

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rag/flow/tests/dsl_examples/hierarchical_merger.json

@@ -0,0 +1,84 @@
+{
+  "components": {
+    "File": {
+        "obj":{
+            "component_name": "File",
+            "params": {
+            }
+        },
+        "downstream": ["Parser:0"],
+        "upstream": []
+    },
+    "Parser:0": {
+        "obj": {
+            "component_name": "Parser",
+            "params": {
+              "setups": {
+                "pdf": {
+                  "parse_method": "deepdoc",
+                  "vlm_name": "",
+                  "lang": "Chinese",
+                  "suffix": [
+                    "pdf"
+                  ],
+                  "output_format": "json"
+                },
+                "spreadsheet": {
+                  "suffix": [
+                    "xls",
+                    "xlsx",
+                    "csv"
+                  ],
+                  "output_format": "html"
+                },
+                "word": {
+                  "suffix": [
+                    "doc",
+                    "docx"
+                  ],
+                  "output_format": "json"
+                },
+                "markdown": {
+                  "suffix": [
+                    "md",
+                    "markdown"
+                  ],
+                  "output_format": "text"
+                },
+                "text": {
+                  "suffix": ["txt"],
+                  "output_format": "json"
+                }
+              }
+          }
+        },
+        "downstream": ["Splitter:0"],
+        "upstream": ["File"]
+    },
+    "Splitter:0": {
+        "obj": {
+            "component_name": "Splitter",
+            "params": {
+              "chunk_token_size": 512,
+              "delimiters": ["\r\n"],
+              "overlapped_percent": 0
+            }
+        },
+        "downstream": ["HierarchicalMerger:0"],
+        "upstream": ["Parser:0"]
+    },
+    "HierarchicalMerger:0": {
+        "obj": {
+            "component_name": "HierarchicalMerger",
+            "params": {
+              "levels": [["^#[^#]"], ["^##[^#]"], ["^###[^#]"], ["^####[^#]"]],
+              "hierarchy": 2
+            }
+        },
+        "downstream": [],
+        "upstream": ["Splitter:0"]
+    }
+  },
+  "path": []
+}
+