RFR: 6674: Use try-with-resource in more places and close un-closed resources

[Henrik Dafgård]

This PR fixes a few places where we didn't close resources properly before and also changes a number of older usages of IOToolkit to instead use try-with-resource.

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Commits:
 - 3d150a42: Fix formatting
 - 428e6409: Use auto-closable in more places and close un-closed resources

Changes: https://git.openjdk.java.net/jmc/pull/33/files
 Webrev: https://webrevs.openjdk.java.net/jmc/33/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/JMC-6674
  Stats: 313 lines in 38 files changed: 28 ins; 151 del; 134 mod
  Patch: https://git.openjdk.java.net/jmc/pull/33.diff
  Fetch: git fetch https://git.openjdk.java.net/jmc pull/33/head:pull/33

PR: https://git.openjdk.java.net/jmc/pull/33