Split Constant to individual literal nodes (#8064)

## Summary

This PR splits the `Constant` enum as individual literal nodes. It
introduces the following new nodes for each variant:
* `ExprStringLiteral`
* `ExprBytesLiteral`
* `ExprNumberLiteral`
* `ExprBooleanLiteral`
* `ExprNoneLiteral`
* `ExprEllipsisLiteral`

The main motivation behind this refactor is to introduce the new AST
node for implicit string concatenation in the coming PR. The elements of
that node will be either a string literal, bytes literal or a f-string
which can be implemented using an enum. This means that a string or
bytes literal cannot be represented by `Constant::Str` /
`Constant::Bytes` which creates an inconsistency.

This PR avoids that inconsistency by splitting the constant nodes into
it's own literal nodes, literal being the more appropriate naming
convention from a static analysis tool perspective.

This also makes working with literals in the linter and formatter much
more ergonomic like, for example, if one would want to check if this is
a string literal, it can be done easily using
`Expr::is_string_literal_expr` or matching against `Expr::StringLiteral`
as oppose to matching against the `ExprConstant` and enum `Constant`. A
few AST helper methods can be simplified as well which will be done in a
follow-up PR.

This introduces a new `Expr::is_literal_expr` method which is the same
as `Expr::is_constant_expr`. There are also intermediary changes related
to implicit string concatenation which are quiet less. This is done so
as to avoid having a huge PR which this already is.

## Test Plan

1. Verify and update all of the existing snapshots (parser, visitor)
2. Verify that the ecosystem check output remains **unchanged** for both
the linter and formatter

### Formatter ecosystem check

#### `main`

| project | similarity index | total files | changed files |

|----------------|------------------:|------------------:|------------------:|
| cpython | 0.75803 | 1799 | 1647 |
| django | 0.99983 | 2772 | 34 |
| home-assistant | 0.99953 | 10596 | 186 |
| poetry | 0.99891 | 317 | 17 |
| transformers | 0.99966 | 2657 | 330 |
| twine | 1.00000 | 33 | 0 |
| typeshed | 0.99978 | 3669 | 20 |
| warehouse | 0.99977 | 654 | 13 |
| zulip | 0.99970 | 1459 | 22 |

#### `dhruv/constant-to-literal`

| project | similarity index | total files | changed files |

|----------------|------------------:|------------------:|------------------:|
| cpython | 0.75803 | 1799 | 1647 |
| django | 0.99983 | 2772 | 34 |
| home-assistant | 0.99953 | 10596 | 186 |
| poetry | 0.99891 | 317 | 17 |
| transformers | 0.99966 | 2657 | 330 |
| twine | 1.00000 | 33 | 0 |
| typeshed | 0.99978 | 3669 | 20 |
| warehouse | 0.99977 | 654 | 13 |
| zulip | 0.99970 | 1459 | 22 |

crates/ruff_linter/src/rules/pydocstyle/helpers.rs

@@ -2,7 +2,6 @@ use std::collections::BTreeSet;
 
 use ruff_python_ast::call_path::from_qualified_name;
 use ruff_python_ast::helpers::map_callable;
-use ruff_python_ast::Expr;
 use ruff_python_semantic::{Definition, SemanticModel};
 use ruff_source_file::UniversalNewlines;
 
@@ -61,13 +60,3 @@ pub(crate) fn should_ignore_definition(
             })
     })
 }
-
-/// Check if a docstring should be ignored.
-pub(crate) fn should_ignore_docstring(docstring: &Expr) -> bool {
-    // Avoid analyzing docstrings that contain implicit string concatenations.
-    // Python does consider these docstrings, but they're almost certainly a
-    // user error, and supporting them "properly" is extremely difficult.
-    docstring
-        .as_constant_expr()
-        .is_some_and(|constant| constant.value.is_implicit_concatenated())
-}

crates/ruff_linter/src/rules/pydocstyle/rules/capitalized.rs

@@ -86,7 +86,7 @@ pub(crate) fn capitalized(checker: &mut Checker, docstring: &Docstring) {
             first_word: first_word.to_string(),
             capitalized_word: capitalized_word.to_string(),
         },
-        docstring.expr.range(),
+        docstring.range(),
     );
 
     diagnostic.set_fix(Fix::safe_edit(Edit::range_replacement(

crates/ruff_linter/src/rules/pydocstyle/rules/newline_after_last_paragraph.rs

@@ -96,8 +96,8 @@ pub(crate) fn newline_after_last_paragraph(checker: &mut Checker, docstring: &Do
                     );
                     diagnostic.set_fix(Fix::safe_edit(Edit::replacement(
                         content,
-                        docstring.expr.end() - num_trailing_quotes - num_trailing_spaces,
-                        docstring.expr.end() - num_trailing_quotes,
+                        docstring.end() - num_trailing_quotes - num_trailing_spaces,
+                        docstring.end() - num_trailing_quotes,
                     )));
                     checker.diagnostics.push(diagnostic);
                 }