added alt worlds prompts

lm_eval/tasks/mmlu/alternative_worlds/mmlu_alternative_worlds_fc.yaml

+group: alternative_worlds_mmlu_fc
+task:
+  - mmlu_style_01_fc
+  - mmlu_style_02_fc
+  - mmlu_style_03_fc
+  - mmlu_style_04_fc
+  - mmlu_style_05_fc
\ No newline at end of file

lm_eval/tasks/mmlu/alternative_worlds/mmlu_alternative_worlds_lo.yaml

+group: alternative_worlds_mmlu_lo
+task:
+  - mmlu_style_01_lo
+  - mmlu_style_02_lo
+  - mmlu_style_03_lo
+  - mmlu_style_04_lo
+  - mmlu_style_05_lo
\ No newline at end of file