[code-reflection] RFR: Create Quoted instance when it's requested

[Mourad Abbay]

This PR moves construction of Quoted instance from constructor to the method that returns it. This simple change will allow us to lazily invoke `opMethod`, something I will work on in a follow up PR.

This changes are based on #420.

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Commit messages:
 - Merge branch 'lambda-model-uniqueness' into Quoted-obj-on-demand
 - Remove unused method
 - Create Quoted instance when it's requested
 - Apply Paul's comments
 - Remove static field as it causes compilation error
 - Define static fields and update comments
 - Rename a test
 - Share the compiler generated code model of a lambda across instances of its proxy class

Changes: https://git.openjdk.org/babylon/pull/422/files
  Webrev: https://webrevs.openjdk.org/?repo=babylon&pr=422&range=00
  Stats: 241 lines in 4 files changed: 106 ins; 117 del; 18 mod
  Patch: https://git.openjdk.org/babylon/pull/422.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/422/head:pull/422

PR: https://git.openjdk.org/babylon/pull/422