RFR: 8299518: HotSpotVirtualMachine shared code across different platforms

[Yi Yang]

harmless refactor to share code across different platforms of VirtualMachineImpl:
1. Shared code to process command response after requesting a command execution
2. Read functionality in SocketInputStream can be reused

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

Commit messages:
 - update year
 - 8299518: HotSpotVirtualMachine shared code across different platforms

Changes: https://git.openjdk.org/jdk/pull/11823/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=11823&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8299518
  Stats: 448 lines in 5 files changed: 87 ins; 240 del; 121 mod
  Patch: https://git.openjdk.org/jdk/pull/11823.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11823/head:pull/11823

PR: https://git.openjdk.org/jdk/pull/11823