Fix instantiated method signatures in error traces

[HertzDevil]

Fixes part of #13566 by including named arguments in the instantiated method signatures that show up in error traces. This PR only touches the traces, not the final error message itself.

Also expands single and double splat arguments. Also uses Call#full_name to prefer T.method over T.class#method for class methods.

[straight-shoota]

I think stringifying the full type signature should be extracted to a helper method. It's a completely separated individual sub task.

I'm also wondering if there could be some generalization applied. This can come later, though.
For example, the stringification of DoubleSplat and named_args is almost identical. Very similar implementations also exist in NamedTuple#to_s and NamedTupleInstanceType#to_s_with_options.