[code-reflection] RFR: Make Quotable a marker interface [v7]

[Mourad Abbay]

> In this PR, we make Quotable a marker interface. This PR is based on #301.

Mourad Abbay has updated the pull request incrementally with one additional commit since the last revision:

  Handle the case where a Quotable instance's class is a Proxy.

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Changes:
  - all: https://git.openjdk.org/babylon/pull/302/files
  - new: https://git.openjdk.org/babylon/pull/302/files/a027bb79..99ec363c

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=babylon&pr=302&range=06
 - incr: https://webrevs.openjdk.org/?repo=babylon&pr=302&range=05-06

  Stats: 63 lines in 3 files changed: 37 ins; 21 del; 5 mod
  Patch: https://git.openjdk.org/babylon/pull/302.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/302/head:pull/302

PR: https://git.openjdk.org/babylon/pull/302