XGC-148: drop commons-io dependency

[vlsi]

Fixes https://issues.apache.org/jira/browse/XGC-148

TODO:

• IOUtils.closeQuitely — replaced with try-with-resources
• IOUtils.toString(Reader) — implemented a function in test (it was used in a single test only)
• IOUtils.copy. Java 9 has InputStream.transferTo(OutputStream)
• IOUtils.toByteArray. Java 9 has InputStream.readAllBytes()
• commons.io.output.ByteArrayOutputStream. I see that there were no consistent use of commons.ByteArrayOutputStream, so I replaced all the usages with java.io.ByteArrayOutputStream
• EndianUtils.readSwappedInteger

[vlsi]

I see the CI checks fail, and I suggest a fix for it: #33

[vlsi]

@simonsteiner1984 , any thoughts?

[vlsi]

Is there a reason of not merging the PR?

Frankly, it looks sad to miss myself here: https://github.com/apache/xmlgraphics-commons/graphs/contributors

[simonsteiner1984]

22e04a9

[vlsi]

@simonsteiner1984 , Thanks for landing this. One request on attribution.

The change went in verbatim — the squashed commit 22e04a9 is byte-for-byte identical to this PR's diff — but it's authored under your name, with mine only in the message body ("by Vladimir Sitnikov"). GitHub keys the Contributors list and profile activity off the commit's Author field, so the mention doesn't register as a contribution.

Since the changes are already in main, I see the following ways to fix the attribution:

1. Re-author the existing commit — amend 22e04a9 to set me as the author:
   git commit --amend --author="Vladimir Sitnikov <sitnikov.vladimir@gmail.com>"
2. Revert and merge the PR: revert 22e04a9, then merge this PR so the change lands as a commit with the correct author.

Either works. Going forward, merging the PR (or passing --author when you cherry-pick) keeps contributor attribution intact. Thanks!