Feature request: Make XP for promotion programmable

[AutumnPizazz]

Before creating

• [X] This is NOT a gameplay feature from Civ VI, BNW, or outside - see Roadmap
• [X] This is NOT a gameplay feature from Vanilla Civ V or from G&K - If so, it should be a comment in https://github.com/yairm210/Unciv/issues/4697

Problem Description

You see, unciv or civ5 define the XP for promotion as 10, 20, 40, 80... But I wish it programmable in mod: Add a property in ModOptions.json like

{
    "isBaseRuleset": true,
    "constants": {
        "baseXPforPromotion": 10,//default as 10
        "incXPperPromotion": 10,//default as 0
        "mulTimeXPperPromtion":1.50//default as 2.00
    }
}

Related Issue Links

No response

Desired Solution

See above.

Alternative Approaches

See above.

Additional Context

No response