RFR: 8322256: Define and document GZIPInputStream concatenated stream semantics [v2]

[Eirik Bjørsnøs]

> Please review this PR with picks up on the excellent work done by @archiecobbs in #18385
> 
> The proposed changes aim to solve two issues with the current `java.util.zip.GZIPInputStream`:
> 
> *  The class parses multiple concatenated GZIP files as a single stream. This behavior is not documented in the API  specification.
> *  Any additional bytes following a trailer which do not form a valid header are discarded and the stream behaves as if the end of stream has been reached. This behavior is not documented in the API  specification.
> 
> Testing:
> 
> * A new test `GZIPInputStreamConcat` verifies the behaviors being specified in this PR 
> * A new test `GZIPInputStreamGzipCommand` verifies decompression of various GZIP files created using the `gzip` command.

Eirik Bjørsnøs has updated the pull request incrementally with one additional commit since the last revision:

  Use {@code InputStream}

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/20787/files
  - new: https://git.openjdk.org/jdk/pull/20787/files/fc2b57e6..a4ce2b83

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=20787&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=20787&range=00-01

  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/20787.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20787/head:pull/20787

PR: https://git.openjdk.org/jdk/pull/20787