Refactor variable assignments and improve script readability in validate-plex-backups.sh and validate-plex-recovery.sh

- Changed inline variable assignments to separate declaration and assignment for clarity.
- Updated condition checks and log messages for better readability and consistency.
- Added a backup of validate-plex-recovery.sh for safety.
- Introduced a new script run-docker-tests.sh for testing setup in Docker containers.
- Enhanced ssh-login.sh to improve condition checks and logging functionality.

github-cli-key-replacement.sh

@@ -1,3 +1,5 @@
+#!/bin/bash
+
 # Check for wget, if not installed, install it
 (type -p wget >/dev/null || (sudo apt update && sudo apt-get install wget -y)) \
     && sudo mkdir -p -m 755 /etc/apt/keyrings