migrate code gen to use protocol list

[sbiscigl]

Description of changes:

Migrate code generation to use protocol list instead of single protocol value. i.e. from s3

  "metadata":{
    "apiVersion":"2006-03-01",
    "checksumFormat":"md5",
    "endpointPrefix":"s3",
    "globalEndpoint":"s3.amazonaws.com",
    "protocol":"rest-xml",
    "protocols":["rest-xml"],
    "serviceAbbreviation":"Amazon S3",
    "serviceFullName":"Amazon Simple Storage Service",
    "serviceId":"S3",
    "signatureVersion":"s3",
    "uid":"s3-2006-03-01",
    "auth":["aws.auth#sigv4"]
  },

This will allow for services to support different protocols, for now we will just select the first protocol that is not CBOR as we do not support it yet.

Check all that applies:

• Did a review by yourself.
• Added proper tests to cover this PR. (If tests are not applicable, explain.)
• Checked if this PR is a breaking (APIs have been changed) change.
• Checked if this PR will not introduce cross-platform inconsistent behavior.
• Checked if this PR would require a ReadMe/Wiki update.

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