feat: add PubMed operator #918 (#1589)

### What problem does this PR solve?

feat: modify the translation of baiduDescription #918
feat: add PubMed operator #918
### Type of change


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

web/src/pages/flow/flow-drawer/index.tsx

@@ -14,6 +14,7 @@ import { useHandleFormValuesChange, useHandleNodeNameChange } from '../hooks';
 import KeywordExtractForm from '../keyword-extract-form';
 import MessageForm from '../message-form';
 import OperatorIcon from '../operator-icon';
+import PubMedForm from '../pubmed-form';
 import RelevantForm from '../relevant-form';
 import RetrievalForm from '../retrieval-form';
 import RewriteQuestionForm from '../rewrite-question-form';
@@ -38,6 +39,7 @@ const FormMap = {
   [Operator.DuckDuckGo]: DuckDuckGoForm,
   [Operator.KeywordExtract]: KeywordExtractForm,
   [Operator.Wikipedia]: WikipediaForm,
+  [Operator.PubMed]: PubMedForm,
 };
 
 const EmptyContent = () => <div>empty</div>;