Add support for PEP 701 (#7376)

## Summary

This PR adds support for PEP 701 in Ruff. This is a rollup PR of all the
other individual PRs. The separate PRs were created for logic separation
and code reviews. Refer to each pull request for a detail description on
the change.

Refer to the PR description for the list of pull requests within this PR.

## Test Plan

### Formatter ecosystem checks

Explanation for the change in ecosystem check:
https://github.com/astral-sh/ruff/pull/7597#issue-1908878183

#### `main`

```
| project      | similarity index  | total files       | changed files     |
|--------------|------------------:|------------------:|------------------:|
| cpython      |           0.76083 |              1789 |              1631 |
| django       |           0.99983 |              2760 |                36 |
| transformers |           0.99963 |              2587 |               319 |
| twine        |           1.00000 |                33 |                 0 |
| typeshed     |           0.99983 |              3496 |                18 |
| warehouse    |           0.99967 |               648 |                15 |
| zulip        |           0.99972 |              1437 |                21 |
```

#### `dhruv/pep-701`

```
| project      | similarity index  | total files       | changed files     |
|--------------|------------------:|------------------:|------------------:|
| cpython      |           0.76051 |              1789 |              1632 |
| django       |           0.99983 |              2760 |                36 |
| transformers |           0.99963 |              2587 |               319 |
| twine        |           1.00000 |                33 |                 0 |
| typeshed     |           0.99983 |              3496 |                18 |
| warehouse    |           0.99967 |               648 |                15 |
| zulip        |           0.99972 |              1437 |                21 |
```

crates/ruff_python_ast/src/nodes.rs

@@ -2600,6 +2600,14 @@ impl Constant {
             _ => false,
         }
     }
+
+    /// Returns `true` if the constant is a string constant that is a unicode string (i.e., `u"..."`).
+    pub fn is_unicode_string(&self) -> bool {
+        match self {
+            Constant::Str(value) => value.unicode,
+            _ => false,
+        }
+    }
 }
 
 #[derive(Clone, Debug, PartialEq, Eq)]
@@ -2620,6 +2628,16 @@ impl Deref for StringConstant {
     }
 }
 
+impl From<String> for StringConstant {
+    fn from(value: String) -> StringConstant {
+        Self {
+            value,
+            unicode: false,
+            implicit_concatenated: false,
+        }
+    }
+}
+
 #[derive(Clone, Debug, PartialEq, Eq)]
 pub struct BytesConstant {
     /// The bytes value as resolved by the parser (i.e., without quotes, or escape sequences, or
@@ -2636,6 +2654,15 @@ impl Deref for BytesConstant {
     }
 }
 
+impl From<Vec<u8>> for BytesConstant {
+    fn from(value: Vec<u8>) -> BytesConstant {
+        Self {
+            value,
+            implicit_concatenated: false,
+        }
+    }
+}
+
 impl From<Vec<u8>> for Constant {
     fn from(value: Vec<u8>) -> Constant {
         Self::Bytes(BytesConstant {
@@ -3207,6 +3234,12 @@ pub struct ParenthesizedExpr {
     /// The underlying expression.
     pub expr: Expr,
 }
+impl ParenthesizedExpr {
+    /// Returns `true` if the expression is may be parenthesized.
+    pub fn is_parenthesized(&self) -> bool {
+        self.range != self.expr.range()
+    }
+}
 impl Ranged for ParenthesizedExpr {
     fn range(&self) -> TextRange {
         self.range