refactor: Introduce crates folder (#2088)

This PR introduces a new `crates` directory and moves all "product" crates into that folder. 

Part of #2059.

crates/ruff_dev/src/generate_options.rs

@@ -0,0 +1,99 @@
+//! Generate a Markdown-compatible listing of configuration options.
+#![allow(clippy::print_stdout, clippy::print_stderr)]
+
+use anyhow::Result;
+use itertools::Itertools;
+use ruff::settings::options::Options;
+use ruff::settings::options_base::{ConfigurationOptions, OptionEntry, OptionField};
+
+use crate::utils::replace_readme_section;
+
+const BEGIN_PRAGMA: &str = "<!-- Begin auto-generated options sections. -->\n";
+const END_PRAGMA: &str = "<!-- End auto-generated options sections. -->";
+
+#[derive(clap::Args)]
+pub struct Args {
+    /// Write the generated table to stdout (rather than to `README.md`).
+    #[arg(long)]
+    pub(crate) dry_run: bool,
+}
+
+fn emit_field(output: &mut String, field: &OptionField, group_name: Option<&str>) {
+    output.push_str(&format!("#### [`{0}`](#{0})\n", field.name));
+    output.push('\n');
+    output.push_str(field.doc);
+    output.push_str("\n\n");
+    output.push_str(&format!("**Default value**: `{}`\n", field.default));
+    output.push('\n');
+    output.push_str(&format!("**Type**: `{}`\n", field.value_type));
+    output.push('\n');
+    output.push_str(&format!(
+        "**Example usage**:\n\n```toml\n[tool.ruff{}]\n{}\n```\n",
+        if group_name.is_some() {
+            format!(".{}", group_name.unwrap())
+        } else {
+            String::new()
+        },
+        field.example
+    ));
+    output.push('\n');
+}
+
+pub fn main(args: &Args) -> Result<()> {
+    let mut output = String::new();
+
+    // Generate all the top-level fields.
+    for field in Options::get_available_options()
+        .into_iter()
+        .filter_map(|entry| {
+            if let OptionEntry::Field(field) = entry {
+                Some(field)
+            } else {
+                None
+            }
+        })
+        .sorted_by_key(|field| field.name)
+    {
+        emit_field(&mut output, &field, None);
+        output.push_str("---\n\n");
+    }
+
+    // Generate all the sub-groups.
+    for group in Options::get_available_options()
+        .into_iter()
+        .filter_map(|entry| {
+            if let OptionEntry::Group(group) = entry {
+                Some(group)
+            } else {
+                None
+            }
+        })
+        .sorted_by_key(|group| group.name)
+    {
+        output.push_str(&format!("### `{}`\n", group.name));
+        output.push('\n');
+        for field in group
+            .fields
+            .iter()
+            .filter_map(|entry| {
+                if let OptionEntry::Field(field) = entry {
+                    Some(field)
+                } else {
+                    None
+                }
+            })
+            .sorted_by_key(|field| field.name)
+        {
+            emit_field(&mut output, field, Some(group.name));
+            output.push_str("---\n\n");
+        }
+    }
+
+    if args.dry_run {
+        print!("{output}");
+    } else {
+        replace_readme_section(&output, BEGIN_PRAGMA, END_PRAGMA)?;
+    }
+
+    Ok(())
+}