Add corners options to some showcases (#44)

* Add corners option for Strixhaven showcases, Amonkhet Invocation, Dungeon Module, Secret Lair Full Art, and Unstable Basics
* Added option to remove name background from Unstable Basics
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Co-authored-by: cajun <12363371+CajunAvenger@users.noreply.github.com>

data/magic-modules.mse-include/information/choices_partition

@@ -0,0 +1,52 @@
+choice:
+	name: before normal
+	choice: 0
+	choice: 1
+	choice: 2
+	choice: 3
+	choice: 4
+	choice: 5
+	choice: 6
+	choice: 7
+	choice: 8
+	choice: 9
+choice: A
+choice:
+	name: after normal, main set
+	choice: B
+	choice: C
+	choice: D
+	choice: E
+	choice: F
+	choice: G
+	choice: H
+	choice: I
+	choice: J
+	choice: K
+	choice: L
+	choice: M
+choice:
+	name: after main set
+	choice: N
+	choice: O
+	choice: P
+	choice: Q
+	choice: R
+	choice: S
+	choice: T
+	choice: U
+	choice: V
+	choice: W
+	choice: X
+	choice: Y
+	choice: Z
+choice:
+	name: help
+	choice: This is the partition selecter
+	choice: You can use this to sort cards in different sublayers
+	choice: 0-9 go before the main count, like face commanders
+	choice: A is the main count
+	choice: B-M go after, but still count in the set total
+	choice: N-Z go over the set total, like #301/300
+	choice: You can change the flip point in the Set tab if you need to
+	choice: with option "Last main partition", which defaults to M