Username before tmp for uploads and downloads


*Originating Project/Creator*
*Affected Component*
*Affected Architectures(s)*
*Related Issue(s)*
*Has Unit Tests (y/n)*
*Builds Without Errors (y/n)*
*Unit Tests Pass (y/n)*
*Documentation Included (y/n)*

Change Description

Uploading and downloading files should use /tmp/\<username>/fprime-uplink. Same for fprime-downlink

Prevent user privilege errors during runtime and prevents the users from stepping on each other

Fill in testing procedures, specific items to focus on for review, or other info to help the team verify these changes are flight-quality.

Note any additional work that will be done relating to this issue.