Musl arm64

[TingDaoK]

Issue #, if available:

• linux-arm64-musl pre built missing #538

Description of changes:

• Add musl arm64 to our pipeline and CI for it
• https://docs.aws.amazon.com/codebuild/latest/userguide/action-runner.html Good way to get a arm64 linux so that we can get rid of qemu! (I tried to do the same for raspberry-pi CI, but it failed to install node for some weird reason :(
• I didn't give any reason for the armv7-musl CI when I added it, here :(. So, get rid of it.

Caveat: package size increased.
Before this change:

npm notice name:          aws-crt                                 
npm notice version:       1.24.2-11-ged1f968                      
npm notice filename:      aws-crt-1.24.2-11-ged1f968.tgz          
npm notice package size:  9.2 MB                                  
npm notice unpacked size: 26.3 MB  

After this change

npm notice name:          aws-crt                                 
npm notice version:       1.24.2-13-g16e1f42                      
npm notice filename:      aws-crt-1.24.2-13-g16e1f42.tgz          
npm notice package size:  11.4 MB                                 
npm notice unpacked size: 31.6 MB 

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.