Implement template strings (#17851)

This PR implements template strings (t-strings) in the parser and
formatter for Ruff.

Minimal changes necessary to compile were made in other parts of the code (e.g. ty, the linter, etc.). These will be covered properly in follow-up PRs.

crates/ruff_python_ast/ast.toml

@@ -433,6 +433,18 @@ See also [JoinedStr](https://docs.python.org/3/library/ast.html#ast.JoinedStr)""
 fields = [{ name = "value", type = "FStringValue" }]
 custom_source_order = true
 
+[Expr.nodes.ExprTString]
+doc = """An AST node that represents either a single-part t-string literal
+or an implicitly concatenated t-string literal.
+
+This type differs from the original Python AST `TemplateStr` in that it
+doesn't join the implicitly concatenated parts into a single string. Instead,
+it keeps them separate and provide various methods to access the parts.
+
+See also [TemplateStr](https://docs.python.org/3/library/ast.html#ast.TemplateStr)"""
+fields = [{ name = "value", type = "TStringValue" }]
+custom_source_order = true
+
 [Expr.nodes.ExprStringLiteral]
 doc = """An AST node that represents either a single-part string literal
 or an implicitly concatenated string literal."""
@@ -539,9 +551,10 @@ doc = "See also [excepthandler](https://docs.python.org/3/library/ast.html#ast.e
 [ExceptHandler.nodes]
 ExceptHandlerExceptHandler = {}
 
-[FStringElement.nodes]
-FStringExpressionElement = { variant = "Expression" }
-FStringLiteralElement = { variant = "Literal" }
+[InterpolatedStringElement.nodes]
+InterpolatedElement = { variant = "Interpolation" }
+InterpolatedStringLiteralElement = { variant = "Literal" }
+
 
 [Pattern]
 doc = "See also [pattern](https://docs.python.org/3/library/ast.html#ast.pattern)"
@@ -565,7 +578,7 @@ TypeParamTypeVarTuple = {}
 TypeParamParamSpec = {}
 
 [ungrouped.nodes]
-FStringFormatSpec = {}
+InterpolatedStringFormatSpec = {}
 PatternArguments = {}
 PatternKeyword = {}
 Comprehension = {}
@@ -581,6 +594,7 @@ Decorator = {}
 ElifElseClause = {}
 TypeParams = {}
 FString = {}
+TString = {}
 StringLiteral = {}
 BytesLiteral = {}
 Identifier = {}