Fix a false positive for Style/RedundantParentheses

This PR fixes a false positive for `Style/RedundantParentheses`
when regexp literal attempts to match against a parenthesized condition.

The presence or absence of parentheses here changes the meaning of the syntax,
so the parentheses are not redundant:

```console
$ ruby-parse -e '/regexp/ =~ (foo || bar)'
(match-with-lvasgn
  (regexp
    (str "regexp")
    (regopt))
  (begin
    (or
      (send nil :foo)
      (send nil :bar))))

$ ruby-parse -e '/regexp/ =~ foo || bar'
(or
  (match-with-lvasgn
    (regexp
      (str "regexp")
      (regopt))
    (send nil :foo))
  (send nil :bar))
```

changelog/fix_false_positive_for_style_redundant_parentheses.md

@@ -0,0 +1 @@
+* [#12606](https://github.com/rubocop/rubocop/pull/12606): Fix a false positive for `Style/RedundantParentheses` when regexp literal attempts to match against a parenthesized condition. ([@koic][])

lib/rubocop/cop/style/redundant_parentheses.rb

@@ -53,7 +53,7 @@ def parens_allowed?(node)
         def ignore_syntax?(node)
           return false unless (parent = node.parent)
 
-          parent.while_post_type? || parent.until_post_type? ||
+          parent.while_post_type? || parent.until_post_type? || parent.match_with_lvasgn_type? ||
             like_method_argument_parentheses?(parent)
         end
 

spec/rubocop/cop/style/redundant_parentheses_spec.rb

@@ -574,6 +574,14 @@ def x
     expect_no_offenses('a...(b || c)')
   end
 
+  it 'accepts regexp literal attempts to match against a parenthesized condition' do
+    expect_no_offenses('/regexp/ =~ (b || c)')
+  end
+
+  it 'accepts variable attempts to match against a parenthesized condition' do
+    expect_no_offenses('regexp =~ (b || c)')
+  end
+
   it 'registers parentheses around `||` logical operator keywords in method definition' do
     expect_offense(<<~RUBY)
       def foo