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

[Mourad Abbay]

> 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

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Changes:
  - all: https://git.openjdk.org/babylon/pull/395/files
  - new: https://git.openjdk.org/babylon/pull/395/files/9e815f03..a49f2790

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=babylon&pr=395&range=02
 - incr: https://webrevs.openjdk.org/?repo=babylon&pr=395&range=01-02

  Stats: 182 lines in 11 files changed: 9 ins; 139 del; 34 mod
  Patch: https://git.openjdk.org/babylon/pull/395.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/395/head:pull/395

PR: https://git.openjdk.org/babylon/pull/395