Fix file upload/download

[jacob-curley-fnal]

Updated the flags for starting Xpra so that the file download path is fixed. Also switched the working directory to be the user's home dir. This way the file explorer dialogs within Xpra will default to the same location that the app dumps its files. Prevents users from needing to dig around in the Xpra file system to find their files.

Resolves #27

[github-actions]

Code Coverage Report - 46 of 117 lines covered ( ⛔ 39.32%)

src - 46 of 117 lines covered ( ⛔ 39.32%)

src/ap_python_starter_kit - 46 of 117 lines covered ( ⛔ 39.32%)

src/ap_python_starter_kit/init.py - 0 of 2 lines covered ( ⛔ 0.00%)

⛔ This file is missing coverage.

src/ap_python_starter_kit/acsys_client.py - 9 of 28 lines covered ( ⛔ 32.14%)

Uncovered lines: ⚠️ 18-19, 21-24, 26-28, 30, 34, 36-38, 40-41, 45-46, 48

src/ap_python_starter_kit/gui.py - 16 of 65 lines covered ( ⛔ 24.62%)

Uncovered lines: ⚠️ 12-13, 20-23, 25-26, 28-31, 33-34, 36, 39, 42, 45, 51, 58-59, 61-65, 67-68, 70-73, 75, 77-82, 84-85, 87-88, 90-91, 95-98

src/ap_python_starter_kit/main.py - 21 of 22 lines covered ( ✅ 95.45%)

Uncovered lines: ⚠️ 47