RFR: 8354337: GHA: Windows build fails with chmod permission error

[Kevin Rushforth]

After a recent update by GitHub to the GHA Windows Server 2022 runner, we get the following error in all GHA test runs:


chmod: changing permissions of '.': Permission denied
chmod: changing permissions of './bin': Permission denied 
...


This PR disables running `chmod -R` on the `artifacts/sdk` dir when doing a GHA build.

The `chmod` is only needed when building artifacts for distribution, and we only use the GHA build for sanity testing, so we can avoid this problem by adding a flag that skips the `chmod` if running on GHA. This is a minimally intrusive solution that would restore our ability to run GHA test builds on Windows without affecting the actual JavaFX build.

I've run a CI build as well as a local build to ensure that the chmod is still being executed.

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Commit messages:
 - 8354337: GHA: Windows build fails with chmod permission error

Changes: https://git.openjdk.org/jfx/pull/1770/files
  Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1770&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8354337
  Stats: 14 lines in 2 files changed: 10 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jfx/pull/1770.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1770/head:pull/1770

PR: https://git.openjdk.org/jfx/pull/1770