[Feature Request]: Implment upgrade script to ease and automate upgrade process

[ssddanbrown]

Describe the feature you'd like

Implement an upgrade script to ease the upgrade process. Can add additional checks for common issues we come across.
Look to https://github.com/snipe/snipe-it/blob/master/upgrade.php for experience implementation. Much of what that script does appears to align with how we do updates already.

Describe the benefits this feature would bring to BookStack users

Easier and less frustrating application of updates.
Potentially less issues reported to us.

Additional context

Suggested by @awarre on discord.

---

Would still need to offer old methods as a backup or to be used by those on older versions.

---

Added note: snipe-it it APGL, would need to build our own script separate without direct reference or copying.

[ssddanbrown]

Added as part of #4206 (https://github.com/BookStackApp/system-cli).