Add aws|ec2Query schema extension

[mtdowling]

Precomputes the bytes needed for AWS Query and EC2 query names so they can be fed directly into FormUrlEncodedSink.

awsQuery_GetMetricDataRequest_S: 1,624 -> 1,150 ns (-29%)
awsQuery_GetMetricDataRequest_M: 7,244 -> 5,369 ns (-26%)
awsQuery_GetMetricDataRequest_L: 12,593 -> 9,281 ns (-26%)

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