RFR: JDK-8302281 - ImageIO objects should implement AutoClosable [v4]

[Markus KARG]

> ImageIO objects, like ImageReader, ImageWrite, ImageInputStream and ImageOutputStream, should implement AutoClosable.
> 
> There is a risk of keeping resources opened longer than needed (or even run into a resource leak with long running processes) as the user cannot use try-with-resources currently. The fact that there is a `dispose()` method to be called is easily missed, as people tend to look for `close()`.
> 
> This is not a big change, but it is useful for those working with ImageIO.

Markus KARG has updated the pull request incrementally with one additional commit since the last revision:

  Corrected @since

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/12098/files
  - new: https://git.openjdk.org/jdk/pull/12098/files/963cb65d..f5a5f091

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=12098&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=12098&range=02-03

  Stats: 3 lines in 3 files changed: 2 ins; 1 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/12098.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12098/head:pull/12098

PR: https://git.openjdk.org/jdk/pull/12098