RFR: 8291457: Clean up lifecycle of CDS dump-time data structures [v2]

[Ioi Lam]

> I've rewritten the following data CDS structures to follow the [C++ rule-of-three](https://en.cppreference.com/w/cpp/language/rule_of_three) to improve their lifecycle handling and fix a memory leak. This is done to prepare for future CDS changes that make more allocations during archive creation.
> 
>> Rule of Three: If a class requires a user-defined destructor, a user-defined copy constructor, or a user-defined copy assignment operator, it almost certainly requires all three.
> 
> - DumpTimeClassInfo
> - DumpTimeClassInfo::DTLoaderConstraint
> - DumpTimeClassInfo::DTVerifierConstraint
> - DumpTimeLambdaProxyClassInfo
> 
> I implemented some of the assignment operators using the [copy-and-swap idiom](https://en.cppreference.com/w/cpp/language/copy_assignment) to handle `Symbol` refcounting. Thanks to @kimbarrett for the suggestion.

Ioi Lam has updated the pull request incrementally with one additional commit since the last revision:

  moved maybe_increment_refcount() to Symbol class; added comments about the need for deep copy

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/9722/files
  - new: https://git.openjdk.org/jdk/pull/9722/files/203348e9..29661dd9

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=9722&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=9722&range=00-01

  Stats: 47 lines in 5 files changed: 28 ins; 10 del; 9 mod
  Patch: https://git.openjdk.org/jdk/pull/9722.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9722/head:pull/9722

PR: https://git.openjdk.org/jdk/pull/9722