RFR: 8339876: Move constant symbol caches to Utf8EntryImpl

[Chen Liang]

Some type descriptors are validated against generic utf8 entries, such as field or method types; we can cache a type descriptor wrapping the content of the utf8 entry if this entry is ever used as a type descriptor.

This patch is more of a code cleanup; it is performance neutral.

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

Commit messages:
 - 8339876: Move constant symbol caches to Utf8EntryImpl

Changes: https://git.openjdk.org/jdk/pull/20957/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20957&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8339876
  Stats: 169 lines in 19 files changed: 56 ins; 82 del; 31 mod
  Patch: https://git.openjdk.org/jdk/pull/20957.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20957/head:pull/20957

PR: https://git.openjdk.org/jdk/pull/20957