fix(aliases): Add missing machine size aliases

[dangra]

Change Summary

What and Why: There were missing aliases in machine size combinations

How: Added them in superfly/fly-go@5591960

 ❯ fly platform vm-sizes
Machines platform
NAME         	CPU CORES	MEMORY
shared-cpu-1x	1        	256 MB 		
shared-cpu-2x	2        	512 MB 		
shared-cpu-4x	4        	1024 MB		
shared-cpu-6x	6        	1536 MB		
shared-cpu-8x	8        	2048 MB		

NAME           	CPU CORES	MEMORY  	
performance-1x 	1        	2048 MB 		
performance-2x 	2        	4096 MB 		
performance-4x 	4        	8192 MB 		
performance-6x 	6        	12288 MB		
performance-8x 	8        	16384 MB		
performance-10x	10       	20480 MB		
performance-12x	12       	24576 MB		
performance-14x	14       	28672 MB		
performance-16x	16       	32768 MB		

NAME     	CPU CORES	MEMORY  	GPU MODEL
a10      	8        	32768 MB	a10           	
a100-40gb	8        	32768 MB	a100-pcie-40gb	
a100-80gb	8        	32768 MB	a100-sxm4-80gb	
l40s     	8        	32768 MB	l40s  

Related to: https://community.fly.io/t/new-shared-cpu-6x-machine-tier/26695

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