[code-reflection] RFR: Add ConstructorRef [v3]

[Maurizio Cimadamore]

On Fri, 18 Apr 2025 15:58:42 GMT, Mourad Abbay <mabbay at openjdk.org> wrote:

>> This is Maurizio's work.
>> This PR tries to make `NewOp` similar to how `InvokeOp` is designed. It does this by adding a descriptor for constructors: `ConstructorRef`.
>> `ConstructorRef` is wrapper around `FunctionType`, providing functionalities for resolution to a reflective instance.
>> Some changes are common between this PR and #393.
>
> Mourad Abbay has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Apply Paul's comments

Thanks @mabbay for shepherding this PR!

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PR Comment: https://git.openjdk.org/babylon/pull/395#issuecomment-2835005097