Feat: Redesign and refactor agent module (#9113)

### What problem does this PR solve?

#9082 #6365

<u> **WARNING: it's not compatible with the older version of `Agent`
module, which means that `Agent` from older versions can not work
anymore.**</u>

### Type of change

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

rag/app/book.py

@@ -69,6 +69,9 @@ def chunk(filename, binary=None, from_page=0, to_page=100000,
         Since a book is long and not all the parts are useful, if it's a PDF,
         please setup the page ranges for every book in order eliminate negative effects and save elapsed computing time.
     """
+    parser_config = kwargs.get(
+        "parser_config", {
+            "chunk_token_num": 512, "delimiter": "\n!?。；！？", "layout_recognize": "DeepDOC"})
     doc = {
         "docnm_kwd": filename,
         "title_tks": rag_tokenizer.tokenize(re.sub(r"\.[a-zA-Z]+$", "", filename))
@@ -89,7 +92,7 @@ def chunk(filename, binary=None, from_page=0, to_page=100000,
 
     elif re.search(r"\.pdf$", filename, re.IGNORECASE):
         pdf_parser = Pdf()
-        if kwargs.get("layout_recognize", "DeepDOC") == "Plain Text":
+        if parser_config.get("layout_recognize", "DeepDOC") == "Plain Text":
             pdf_parser = PlainParser()
         sections, tbls = pdf_parser(filename if not binary else binary,
                                     from_page=from_page, to_page=to_page, callback=callback)