Correct this in field and accessor decorators (#3761)

This release changes the value of this in initializers for class field and accessor decorators from the module-level this value to the appropriate this value for the decorated element (either the class or the instance). It was previously incorrect due to lack of test coverage. Here's an example of a decorator that doesn't work without this change:

const dec = () => function() { this.bar = true }
class Foo { @dec static foo }
console.log(Foo.bar) // Should be "true"

Allow es2023 as a target environment (#3762)

TypeScript recently added es2023 as a compilation target, so esbuild now supports this too. There is no difference between a target of es2022 and es2023 as far as esbuild is concerned since the 2023 edition of JavaScript doesn't introduce any new syntax features.