add support for eml file parser (#1768)

### What problem does this PR solve?

add support for eml file parser
#1363

### Type of change

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

---------

Co-authored-by: Zhedong Cen <cenzhedong2@126.com>
Co-authored-by: Kevin Hu <kevinhu.sh@gmail.com>

rag/svr/task_executor.py

@@ -45,7 +45,7 @@ from rag.nlp import search, rag_tokenizer
 from io import BytesIO
 import pandas as pd
 
-from rag.app import laws, paper, presentation, manual, qa, table, book, resume, picture, naive, one, audio, knowledge_graph
+from rag.app import laws, paper, presentation, manual, qa, table, book, resume, picture, naive, one, audio, knowledge_graph, email
 
 from api.db import LLMType, ParserType
 from api.db.services.document_service import DocumentService
@@ -69,6 +69,7 @@ FACTORY = {
     ParserType.PICTURE.value: picture,
     ParserType.ONE.value: one,
     ParserType.AUDIO.value: audio,
+    ParserType.EMAIL.value: email,
     ParserType.KG.value: knowledge_graph
 }