Configurable temporary file options, leave, respect TMPDIR environment, etc.

https://github.com/jgitver/jgitver-maven-plugin/blob/c14645a1900b47ac92c516319a987e6173e93006/src/main/java/fr/brouillard/oss/jgitver/JGitverUtils.java#L86

My problems ( and yes, I realize this is a way out there outlier ):
- The DevOps controls the pipeline and are building jobs in a container.
- The pipeline is doing some post build actions, and end up looking for the /tmp/pom98791734.jgitver-maven-plugin.xml file to read.
- The file is not there as it was "deleteOnExit()"
- I think the post build actions are in a different container and the old /tmp files are gone anyway.

Idea:
- have the temporary directory not be java.io.File's choice, but maybe use and environment variable: e.g. TMPDIR
- have an option to leave the temporary file around ( yea, messy expect for odd-ball situations )

Othewise, this is a fantastic plugin and truly has been working great in more normal situations. >> Thank you!! <<

Open to your thoughts, especially if you have ever run into this before.