[code-reflection] RFR: Code model attribute [v4]

[Adam Sotona]

> This is experimental serialization of code model into a custom method attribute.
> 
> I've performed brief comparison on `BytecodeTest` as a representant of class with majority of methods annotated with `@CodeReflection`.
> 
> Compiled size of the `BytecodeTest` class (with text-encoded code models) is 121288 bytes, CP contains 1612 entries.
> Cleaned size of the class (removed text-encoded code models and their static initialization) is 32801 bytes, CP contains 1277 entries.
> Size with models encoded in custom attributes is 74541 bytes, CP contains 1435 entries.
> 
> Proportional size of the custom attributes vs. text-encoded fields is 37% (47% of the CP entries).

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

  typo

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Changes:
  - all: https://git.openjdk.org/babylon/pull/282/files
  - new: https://git.openjdk.org/babylon/pull/282/files/72721a9b..e8dcde54

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=babylon&pr=282&range=03
 - incr: https://webrevs.openjdk.org/?repo=babylon&pr=282&range=02-03

  Stats: 2 lines in 1 file changed: 0 ins; 1 del; 1 mod
  Patch: https://git.openjdk.org/babylon/pull/282.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/282/head:pull/282

PR: https://git.openjdk.org/babylon/pull/282