This PR will implement pass-through keyword arguments for simple cases of calling core methods or calling other keyword-receiving methods. It is meant as a starting point to fully support pass-through of as many forms of keyword-based invocation as possible.

IR changes

• Associate the kwargs hash with the CallInstr directly, so the call has all metadata for both positional and keyword arguments.

Core changes

• Introduce annotations and processing to allow specifying keyword-receiving overloads.
• Identify and modify an existing keyword-argument core method to have a specialized form and redirect generic forms to it. Any methods that accept a single keyword like exception: or nonblock: would be good candidates for now.

JIT changes

Caller side

The caller side indy optimizations can be implemented early and provides benefits without the rest due to moving hash construction and flags-setting into the call site.

• Embed keywords and kwargs layout into the invokedynamic call site, passing all elements through without constructing a Hash.
• Implement fallback call site logic that just constructs the hash, sets appropriate flags, and passes it as before.

Callee side

• Wire up invokedynamic callee side to discover and bind specialized keyword argument paths, similar to the eager arity-splitting logic already introduced.