Pass ParserOptions to the parser (#16220)

## Summary

This is part of the preparation for detecting syntax errors in the
parser from https://github.com/astral-sh/ruff/pull/16090/. As suggested
in [this
comment](https://github.com/astral-sh/ruff/pull/16090/#discussion_r1953084509),
I started working on a `ParseOptions` struct that could be stored in the
parser. For this initial refactor, I only made it hold the existing
`Mode` option, but for syntax errors, we will also need it to have a
`PythonVersion`. For that use case, I'm picturing something like a
`ParseOptions::with_python_version` method, so you can extend the
current calls to something like

```rust
ParseOptions::from(mode).with_python_version(settings.target_version)
```

But I thought it was worth adding `ParseOptions` alone without changing
any other behavior first.

Most of the diff is just updating call sites taking `Mode` to take
`ParseOptions::from(Mode)` or those taking `PySourceType`s to take
`ParseOptions::from(PySourceType)`. The interesting changes are in the
new `parser/options.rs` file and smaller parts of `parser/mod.rs` and
`ruff_python_parser/src/lib.rs`.

## Test Plan

Existing tests, this should not change any behavior.

crates/ruff_python_formatter/tests/fixtures.rs

@@ -11,7 +11,7 @@ use crate::normalizer::Normalizer;
 use ruff_formatter::FormatOptions;
 use ruff_python_ast::comparable::ComparableMod;
 use ruff_python_formatter::{format_module_source, format_range, PreviewMode, PyFormatOptions};
-use ruff_python_parser::{parse, AsMode};
+use ruff_python_parser::{parse, ParseOptions};
 use ruff_source_file::{LineIndex, OneIndexed};
 use ruff_text_size::{TextRange, TextSize};
 
@@ -393,14 +393,14 @@ fn ensure_unchanged_ast(
     let source_type = options.source_type();
 
     // Parse the unformatted code.
-    let mut unformatted_ast = parse(unformatted_code, source_type.as_mode())
+    let mut unformatted_ast = parse(unformatted_code, ParseOptions::from(source_type))
         .expect("Unformatted code to be valid syntax")
         .into_syntax();
     Normalizer.visit_module(&mut unformatted_ast);
     let unformatted_ast = ComparableMod::from(&unformatted_ast);
 
     // Parse the formatted code.
-    let mut formatted_ast = parse(formatted_code, source_type.as_mode())
+    let mut formatted_ast = parse(formatted_code, ParseOptions::from(source_type))
         .expect("Formatted code to be valid syntax")
         .into_syntax();
     Normalizer.visit_module(&mut formatted_ast);