Adds a 'slot nickname' field for easily ID'ing chara slots #2668

Job	Run time
Lint with OpenDream	21s
Compile Maps	45s
Find Maps to Test	8s
Windows Build	1m 7s
Run Linters	1m 23s
Alternate Tests	0s
Unit Tests (derelict_almayer) / run_unit_tests	3m 8s
Check Alternate Tests	0s
Unit Tests (new_varadero_repaired) / run_unit_tests	26s
Unit Tests (prison_station_fop) / run_unit_tests	41s
Unit Tests (rover) / run_unit_tests	33s
Unit Tests (runtime) / run_unit_tests	2m 39s
Unit Tests (runtime_multiz) / run_unit_tests	2m 27s
Unit Tests (shivas_snowball) / run_unit_tests	27s
Unit Tests (sorokyne_strata) / run_unit_tests	2m 15s
Unit Tests (whiskey_outpost_v2) / run_unit_tests	40s
Unit Tests (almayer) / run_unit_tests	3m 0s
Unit Tests (chinook) / run_unit_tests	2m 52s
Unit Tests (chapaev) / run_unit_tests	2m 42s
Unit Tests (bigredv2) / run_unit_tests	2m 54s
Unit Tests (corsat) / run_unit_tests	3m 6s
Unit Tests (desert_dam) / run_unit_tests	3m 3s
Unit Tests (fiorina_sciannex) / run_unit_tests	2m 46s
Unit Tests (golden_arrow) / run_unit_tests	2m 43s
Unit Tests (golden_arrow_classic) / run_unit_tests	2m 51s
Unit Tests (ice_colony_v1) / run_unit_tests	2m 50s
Unit Tests (ice_colony_v2) / run_unit_tests	3m 2s
Unit Tests (kutjevo) / run_unit_tests	2m 55s
Unit Tests (lv522_chances_claim) / run_unit_tests	2m 56s
Unit Tests (lv624) / run_unit_tests	2m 53s
Unit Tests (new_varadero) / run_unit_tests	2m 49s
Unit Tests (lv624_repaired) / run_unit_tests	2m 47s
	1h 3m 9s

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