RFR: 8368050: Validation missing in ClassFile signature factories [v2]

[Chen Liang]

> The Signature modeling in the ClassFile API is missing some validations required by JVMS, notably identifier character restrictions and void type restrictions. In addition, the model currently uses `ClassDesc` to indicate a simple name for an inner class signature, which is incorrect, and this patch proposes to deprecate that API for removal.

Chen Liang has updated the pull request incrementally with one additional commit since the last revision:

  More bugs

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Changes:
  - all: https://git.openjdk.org/jdk/pull/27380/files
  - new: https://git.openjdk.org/jdk/pull/27380/files/074c5418..8de7e6df

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=27380&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=27380&range=00-01

  Stats: 4 lines in 3 files changed: 2 ins; 1 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/27380.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27380/head:pull/27380

PR: https://git.openjdk.org/jdk/pull/27380