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/main.rs

@@ -0,0 +1,65 @@
+//! This crate implements an internal CLI for developers of Ruff.
+//!
+//! Within the ruff repository you can run it with `cargo dev`.
+
+mod generate_all;
+mod generate_cli_help;
+mod generate_json_schema;
+mod generate_options;
+mod generate_rules_table;
+mod print_ast;
+mod print_cst;
+mod print_tokens;
+mod round_trip;
+mod utils;
+
+use anyhow::Result;
+use clap::{Parser, Subcommand};
+
+const ROOT_DIR: &str = concat!(env!("CARGO_MANIFEST_DIR"), "/../../");
+
+#[derive(Parser)]
+#[command(author, version, about, long_about = None)]
+#[command(propagate_version = true)]
+struct Args {
+    #[command(subcommand)]
+    command: Command,
+}
+
+#[derive(Subcommand)]
+enum Command {
+    /// Run all code and documentation generation steps.
+    GenerateAll(generate_all::Args),
+    /// Generate JSON schema for the TOML configuration file.
+    GenerateJSONSchema(generate_json_schema::Args),
+    /// Generate a Markdown-compatible table of supported lint rules.
+    GenerateRulesTable(generate_rules_table::Args),
+    /// Generate a Markdown-compatible listing of configuration options.
+    GenerateOptions(generate_options::Args),
+    /// Generate CLI help.
+    GenerateCliHelp(generate_cli_help::Args),
+    /// Print the AST for a given Python file.
+    PrintAST(print_ast::Args),
+    /// Print the LibCST CST for a given Python file.
+    PrintCST(print_cst::Args),
+    /// Print the token stream for a given Python file.
+    PrintTokens(print_tokens::Args),
+    /// Run round-trip source code generation on a given Python file.
+    RoundTrip(round_trip::Args),
+}
+
+fn main() -> Result<()> {
+    let args = Args::parse();
+    match &args.command {
+        Command::GenerateAll(args) => generate_all::main(args)?,
+        Command::GenerateJSONSchema(args) => generate_json_schema::main(args)?,
+        Command::GenerateRulesTable(args) => generate_rules_table::main(args)?,
+        Command::GenerateOptions(args) => generate_options::main(args)?,
+        Command::GenerateCliHelp(args) => generate_cli_help::main(args)?,
+        Command::PrintAST(args) => print_ast::main(args)?,
+        Command::PrintCST(args) => print_cst::main(args)?,
+        Command::PrintTokens(args) => print_tokens::main(args)?,
+        Command::RoundTrip(args) => round_trip::main(args)?,
+    }
+    Ok(())
+}