Refactor: rename rmSpace to remove_redundant_spaces (#10796)

### What problem does this PR solve?

- rename rmSpace to remove_redundant_spaces
- move clean_markdown_block to common module
- add unit tests for remove_redundant_spaces and clean_markdown_block

### Type of change

- [x] Refactoring

---------

Signed-off-by: Jin Hai <haijin.chn@gmail.com>

common/float_utils.py

@@ -0,0 +1,46 @@
+#
+#  Copyright 2025 The InfiniFlow Authors. All Rights Reserved.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+#
+
+def get_float(v):
+    """
+    Convert a value to float, handling None and exceptions gracefully.
+
+    Attempts to convert the input value to a float. If the value is None or
+    cannot be converted to float, returns negative infinity as a default value.
+
+    Args:
+        v: The value to convert to float. Can be any type that float() accepts,
+           or None.
+
+    Returns:
+        float: The converted float value if successful, otherwise float('-inf').
+
+    Examples:
+        >>> get_float("3.14")
+        3.14
+        >>> get_float(None)
+        -inf
+        >>> get_float("invalid")
+        -inf
+        >>> get_float(42)
+        42.0
+    """
+    if v is None:
+        return float('-inf')
+    try:
+        return float(v)
+    except Exception:
+        return float('-inf')