Reworked cost adjuster logic for better support of X and cost modification effects:

Improves:
* refactor: split CostAdjuster logic in multiple parts - prepare X, prepare cost, increase cost, reduce cost;
* refactor: improved VariableManaCost to support min/max values, playable and AI calculations, test framework;
* refactor: improved EarlyTargetCost to support mana costs too (related to #13023);
* refactor: migrated some cards with CostAdjuster and X to EarlyTargetCost (Knollspine Invocation, etc - related to #13023);
* refactor: added shared code for "As an additional cost to cast this spell, discard X creature cards";
* refactor: added shared code for "X is the converted mana cost of the exiled card";
* tests: added dozens tests with cost adjusters;

Bug fixes:
* game: fixed that some cards with CostAdjuster ignore min/max limits for X (allow to choose any X, example: Scorched Earth, Open The Way);
* game: fixed that some cards ask to announce already defined X values (example: Bargaining Table);
* game: fixed that some cards with CostAdjuster do not support combo with other cost modification effects;
* game, gui: fixed missing game logs about predefined X values;
* game, gui: fixed wrong X icon for predefined X values;

Test framework:
* test framework: added X min/max check for wrong values;
* test framework: added X min/max info in miss X value announce;
* test framework: added check to find duplicated effect bugs (see assertNoDuplicatedEffects);

Cards:
* Open The Way - fixed that it allow to choose any X without limits (close #12810);
* Unbound Flourishing - improved combo support for activated abilities with predefined X mana costs like Bargaining Table;

Mage.Server.Plugins/Mage.Player.Human/src/mage/player/human/HumanPlayer.java

@@ -1709,6 +1709,8 @@ public class HumanPlayer extends PlayerImpl {
             if (response.getInteger() != null) {
                 break;
             }
+
+            // TODO: add response verify here
         }
 
         if (response.getInteger() != null) {