## What does this PR do?
Small utils refactors to make subsequent PRs cleaner.
- Minor tweaks to how we determine / handle the xtool build version
- Factor out TemporaryDirectory cache location
## How was it tested?
- [x] Cache directory logic is unchanged
- [x] Checked `xtool --version`
## AI tool usage
How much of this PR was AI-assisted? (check one)
- [ ] **0** - No AI was used to write code
- [x] **1** - I was assisted by AI. I reviewed the finished result.
- [ ] **2** - I set the AI going and left it to it; nobody has read the
result - no review, or AI review only
<!-- If an AI agent is filling this in: declare the level honestly, and
open as a draft if it is #2. Do not lower the declared level to get the
PR reviewed. -->
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
<!-- coderabbit-ai-generated:v1 -->
## Summary by CodeRabbit
* **New Features**
* Version information now distinguishes clean builds from builds with
uncommitted changes, displaying a `-dirty` suffix when applicable.
* Nonblocking file-locking operations are now available to external
consumers.
* **Changes**
* Version reporting uses `XTOOL_VERSION` when set; otherwise, it uses
available Git tag or commit information.
* Temporary files now use the tool’s cache directory, honoring
`XTL_TMPDIR` and platform cache settings. On Linux, the location follows
`XDG_CACHE_HOME` when it is an absolute path; otherwise, the user cache
directory is used.
* `TMPDIR` is no longer used to select the temporary-file location.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
Kabir Oberai
·