[code-reflection] RFR: New model store implementation [v3]

[Adam Sotona]

> This PR adds an alternative code model storage implementation.
> 
> With the new implementation compiler attaches a code-model attribute to the synthesized helper method. The method then returns the model by `invokedynamic` of a bootstrap method that reads and materializes the attribute at runtime.
> 
> The new implementation can be selected by setting the compiler option `codeModelStorageOption` to `"CODE_MODEL_ATTRIBUTE"`.
> 
> Please review.
> 
> Thanks,
> Adam

Adam Sotona has updated the pull request incrementally with one additional commit since the last revision:

  storing TypeElement as tree

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Changes:
  - all: https://git.openjdk.org/babylon/pull/654/files
  - new: https://git.openjdk.org/babylon/pull/654/files/8ab47cd0..62ec88d9

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=babylon&pr=654&range=02
 - incr: https://webrevs.openjdk.org/?repo=babylon&pr=654&range=01-02

  Stats: 121 lines in 3 files changed: 87 ins; 5 del; 29 mod
  Patch: https://git.openjdk.org/babylon/pull/654.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/654/head:pull/654

PR: https://git.openjdk.org/babylon/pull/654