feat: 完善文档分块参数配置

- 支持自定义正则匹配内容保留开关及配置持久化

- 约束分块重叠长度始终小于分块长度

- 补充中英文交互文案

easyflow-ui-admin/app/src/locales/langs/en-US/documentCollection.json

@@ -159,6 +159,9 @@
     "chunkSize": "SegmentLength",
     "overlapSize": "SegmentOverlap",
     "regex": "RegularExpression",
+    "regexMatchHandling": "Matched content",
+    "retainRegexMatch": "Keep in next chunk",
+    "discardRegexMatch": "Discard",
     "document": "Document",
     "simpleDocumentSplitter": "SimpleDocumentSplitter",
     "simpleTokenizeSplitter": "SimpleTokenizeSplitter",