RFR: 8307143: CredentialsCache.cacheName should not be static [v2]

[Weijun Wang]

> The CC can be loaded with any file and its name is not static.
> 
> `MemoryCredentialsCache` is removed since it's not used anywhere. We've already supported native ccache reading directly with JNI method `Credentials::acquireDefaultNativeCreds`.

Weijun Wang has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains two commits:

 - merge
 - the fix

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

Changes: https://git.openjdk.org/jdk/pull/13737/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13737&range=01
  Stats: 165 lines in 4 files changed: 54 ins; 82 del; 29 mod
  Patch: https://git.openjdk.org/jdk/pull/13737.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13737/head:pull/13737

PR: https://git.openjdk.org/jdk/pull/13737