Local codegen fixtures

Put a .js, .cjs, .mjs, .jsx, .ts, .cts, .mts, or .tsx reproduction in this directory (subdirectories are supported). fixtures.test.ts parses each file in unambiguous mode and checks both the normal and source-map printers against Rust oxc_codegen.

Use a hand-built AST test for input shapes a parser cannot produce, such as historical TS-ESLint AST layouts. See test/print.test.ts for that style of test.