[crac] RFR: Handle open file descriptors with configurable policies

[Radim Vansa]

When the application does not close some file descriptors through Resources we can use `jdk.crac.fd-policy.checkpoint` and `jdk.crac.fd-policy.restore` to configure the behaviour.

These properties can specify a list of File.pathSeparator-separated key=value pairs, where the key can be one of:

* numeric file descriptor
* path using 'glob' pattern matching (see FileSystem.getPathMatcher() for details)
* keywords FIFO and SOCKET that match pipes and sockets

The value should match one of possible values from OpenFDPolicies.BeforeCheckpoint and OpenFDPolicies.AfterRestore

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Commit messages:
 - Handle open file descriptors with configurable policies

Changes: https://git.openjdk.org/crac/pull/69/files
 Webrev: https://webrevs.openjdk.org/?repo=crac&pr=69&range=00
  Stats: 1072 lines in 15 files changed: 1035 ins; 15 del; 22 mod
  Patch: https://git.openjdk.org/crac/pull/69.diff
  Fetch: git fetch https://git.openjdk.org/crac.git pull/69/head:pull/69

PR: https://git.openjdk.org/crac/pull/69