Warn when new slotmin/slotmax value will cause slots to not work (#4583)

* Properly handle slotmin/slotmax rules

* Use a variable to reduce config calls. No reason to process differently half way through a command anyways.

* Update redbot/cogs/economy/economy.py

* Add positive int converter for slotmin/slotmax

* Option to allow bad mins and maxes.

* Update economy.py

Co-authored-by: jack1142 <6032823+jack1142@users.noreply.github.com>

redbot/cogs/economy/converters.py

@@ -0,0 +1,22 @@
+from typing import NewType, TYPE_CHECKING
+
+from redbot.core.commands import BadArgument
+from redbot.core.i18n import Translator
+from redbot.core.utils.chat_formatting import inline
+
+_ = Translator("Economy", __file__)
+
+# Duplicate of redbot.cogs.cleanup.converters.PositiveInt
+PositiveInt = NewType("PositiveInt", int)
+if TYPE_CHECKING:
+    positive_int = PositiveInt
+else:
+
+    def positive_int(arg: str) -> int:
+        try:
+            ret = int(arg)
+        except ValueError:
+            raise BadArgument(_("{arg} is not an integer.").format(arg=inline(arg)))
+        if ret <= 0:
+            raise BadArgument(_("{arg} is not a positive integer.").format(arg=inline(arg)))
+        return ret