Graves Rewrite

What have you done in this MR?

• Rewrote graves from scratch using new systems and abundant unit testing
• Fixed a race condition bug that would prevent classes implementing PersistWorld from properly... persisting
• Fixed a bug where graves were (still) too generous
• Fixed a bug where graves would not persist across server reboots
• Fixed a bug where graves would not recognize a relogged player
• Fixed numerous other bugs with graves, see the unit tests for complete coverage and what all now works.
• Grave system now supports quest requirements

Testers:

• Make sure you can change your grave at Father Aereck
• Make sure you can't change your grave to one that requires a quest
• Make sure you can't change your grave while you have a grave active (use ::forcegravedeath to force a death that spawns a grave)
• Make sure all graves take their allotted amount of time to respawn
• Make sure blessing graves requires 70 prayer and adds your available prayer points (as minutes) to the timer in an amount that does not exceed 60.
• Make sure repairing graves requires 2 prayer and adds your available prayer points (as minutes) to the timer in an amount that does not exceed 5.
• Make sure graves persist and continue to function normally across relogs

Everything else should be covered by the unit tests.

Implementation Source (and additional info for testing, if you wish): https://runescape.wiki/w/Gravestone?oldid=854455

Are there any tricky things testers should keep an eye out for?

• No

• Yes, as follows:

• I have tested these changes thoroughly.

• This requires extra testing due to changes to architecture or other similarly risky changes.

• I used the Thanos Tool for any JSON edits, I did not edit any JSON files by hand (MR will be rejected if there are manual JSON edits).

• I acknowledge that this contribution will be released under the AGPL license.