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

[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.

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Commit messages:
 - added operator= to complete the rule-of-three
 - use c++ copy-and-swap idiom
 - lint
 - fixed c++
 - 8291457: Clean up lifecycle of CDS dump-time data structures

Changes: https://git.openjdk.org/jdk/pull/9722/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=9722&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8291457
  Stats: 195 lines in 6 files changed: 91 ins; 42 del; 62 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