Add .doc file parser. (#497)

### What problem does this PR solve?
Add `.doc` file parser, using tika.
```
pip install tika
```
```
from tika import parser
from io import BytesIO

def extract_text_from_doc_bytes(doc_bytes):
    file_like_object = BytesIO(doc_bytes)
    parsed = parser.from_buffer(file_like_object)
    return parsed["content"]
```
### Type of change

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

---------

Co-authored-by: chrysanthemum-boy <fannc@qq.com>

rag/app/naive.py

@@ -10,6 +10,7 @@
 #  See the License for the specific language governing permissions and
 #  limitations under the License.
 #
+from tika import parser
 from io import BytesIO
 from docx import Document
 import re
@@ -154,9 +155,17 @@ def chunk(filename, binary=None, from_page=0, to_page=100000,
         sections = [(l, "") for l in sections if l]
         callback(0.8, "Finish parsing.")
 
+    elif re.search(r"\.doc$", filename, re.IGNORECASE):
+        callback(0.1, "Start to parse.")
+        binary = BytesIO(binary)
+        doc_parsed = parser.from_buffer(binary)
+        sections = doc_parsed['content'].split('\n')
+        sections = [(l, "") for l in sections if l]
+        callback(0.8, "Finish parsing.")
+
     else:
         raise NotImplementedError(
-            "file type not supported yet(docx, pdf, txt supported)")
+            "file type not supported yet(doc, docx, pdf, txt supported)")
 
     chunks = naive_merge(
         sections, parser_config.get(