[REVIEW] NXCM-5302 Protect against staging.xml corruption

Enhance existing code to provide temp file handling for storing configuration files.

https://issues.sonatype.org/browse/NXCM-5302 - Protect against staging.xml corruption

Nexus already had interfaces for this use-case, although I couldn't find any existing implementations. I did rename a misspelled interface so if anyone knows of code that implemented ConfigurationWritter, please speak up now :)
I did try to confirm first by searching https://github.com/search?q=ConfigurationWritter&ref=cmdform&type=Code