RFR: 8320362: Load anchor certificates from Keychain keystore [v3]

[Alexey Bakhtin]

> Please review the proposed fix.
> 
> The patch loads system root certificates from the MacOS Keychain with TrustSettings.
> It allows to build a trusted certificate path using the MacOS Keychain store only.

Alexey Bakhtin has updated the pull request incrementally with one additional commit since the last revision:

  Add KeychainStore-ROOT keystore for root certificates

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/16722/files
  - new: https://git.openjdk.org/jdk/pull/16722/files/db98b7c2..8fdea0f2

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=16722&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=16722&range=01-02

  Stats: 169 lines in 3 files changed: 121 ins; 21 del; 27 mod
  Patch: https://git.openjdk.org/jdk/pull/16722.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16722/head:pull/16722

PR: https://git.openjdk.org/jdk/pull/16722