[Backport maintenance/2.15.x] Fix missing-param-doc FP

doc/whatsnew/fragments/7827.false_positive

@@ -0,0 +1,3 @@
+Fix ``missing-param-doc`` false positive when function parameter has an escaped underscore.
+
+Closes #7827

pylint/extensions/_check_docs_utils.py

@@ -471,7 +471,7 @@ class GoogleDocstring(Docstring):
 
     re_param_line = re.compile(
         rf"""
-        \s*  ((?:\\?\*{{0,2}})?\w+)     # identifier potentially with asterisks
+        \s*  ((?:\\?\*{{0,2}})?[\w\\]+) # identifier potentially with asterisks or escaped `\`
         \s*  ( [(]
             {re_multiple_type}
             (?:,\s+optional)?

tests/functional/ext/docparams/parameter/missing_param_doc_required_Google.py

@@ -433,3 +433,15 @@ def test_finds_multiple_complex_types_google(
         named_arg_nine,
         named_arg_ten,
     )
+
+def test_escape_underscore(something: int, raise_: bool = False) -> bool:
+    """Tests param with escaped _ is handled correctly.
+
+    Args:
+        something: the something
+        raise\\_: the other
+
+    Returns:
+        something
+    """
+    return something and raise_