feat(challenges): add consecutive-numbers

challenges/consecutive-numbers/test/1/input.txt

@@ -0,0 +1,6 @@
+7
+1
+2
+5
+3
+4

challenges/consecutive-numbers/test/1/output.txt

@@ -0,0 +1,2 @@
+1 ; 2
+3 ; 4

challenges/consecutive-numbers/test/3/input.txt

@@ -0,0 +1,4 @@
+1
+4
+3
+5

challenges/consecutive-numbers/test/4/input.txt

@@ -0,0 +1,4 @@
+1
+4
+5
+3

challenges/consecutive-numbers/test/4/output.txt

@@ -0,0 +1 @@
+4 ; 5

challenges/consecutive-numbers/test/5/input.txt

@@ -0,0 +1,8 @@
+5
+1
+2
+3
+8
+-5
+-4
+7

challenges/consecutive-numbers/test/5/output.txt

@@ -0,0 +1,3 @@
+1 ; 2
+2 ; 3
+-5 ; -4