[code-reflection] RFR: Structured type definition [v2]

[Paul Sandoz]

> Replace the currently implementation of `TypeDefinition` with a more general tree structure, which is the boundary between the runtime and serialized form.
> 
> This should help when/if we devise a richer modeling of Java types

Paul Sandoz has updated the pull request incrementally with one additional commit since the last revision:

  Simplify.

-------------

Changes:
  - all: https://git.openjdk.org/babylon/pull/23/files
  - new: https://git.openjdk.org/babylon/pull/23/files/8600a647..b075c902

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=babylon&pr=23&range=01
 - incr: https://webrevs.openjdk.org/?repo=babylon&pr=23&range=00-01

  Stats: 37 lines in 2 files changed: 19 ins; 13 del; 5 mod
  Patch: https://git.openjdk.org/babylon/pull/23.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/23/head:pull/23

PR: https://git.openjdk.org/babylon/pull/23