Add new public game modifiers 🙂 (#3500)

## Description:

Adds 5 new public game modifiers to the Special game mode modifier pool:

- **Ports Disabled** - disables port construction, focus on factories
- **Nukes Disabled** - disables atom bombs, hydrogen bombs, MIRVs,
missile silos and SAM launchers
- **SAMs Disabled** - disables SAM launchers (thats funny, you cant
protect against nukes, have to space out your stuff) (mutually exclusive
with nukes disabled)
- **1M Starting Gold** - gives all players 1M starting gold (was
requested by people, new chill tier alongside existing 5M and 25M)
- **4min Peace Time** - grants 4 minutes of PVP spawn immunity

All `PublicGameModifiers` boolean fields are now optional - inactive
modifiers are omitted from game JSON instead of being serialized as
`false` (stop bloating the JSON size)

I think we have enough modifiers now :) Good variety

## Please complete the following:

- [X] I have added screenshots for all UI updates
- [X] I process any text displayed to the user through translateText()
and I've added it to the en.json file
- [X] I have added relevant tests to the test directory
- [X] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced

## Please put your Discord username so you can be contacted if a bug or
regression is found:

FloPinguin

resources/lang/en.json

@@ -500,7 +500,15 @@
     "starting_gold_label": "Starting Gold",
     "gold_multiplier": "x{amount} Gold Multiplier",
     "disable_alliances": "Alliances Disabled",
-    "disable_alliances_label": "Alliances"
+    "disable_alliances_label": "Alliances",
+    "ports_disabled": "Ports Disabled",
+    "ports_disabled_label": "Ports",
+    "nukes_disabled": "Nukes Disabled",
+    "nukes_disabled_label": "Nukes",
+    "sams_disabled": "SAMs Disabled",
+    "sams_disabled_label": "SAMs",
+    "peace_time": "4min Peace",
+    "peace_time_label": "PVP Immunity"
   },
   "select_lang": {
     "title": "Select Language"