PowerShell: Pipe/stream encoding issues with ciphertext to stdout or from stdin

[juneb]

In a PowerShell console, the following command patterns generate 'Unsupported type 63 discovered in data stream' errors:

• 'hello' | aws-crypto -e -m key=$cmkArn -i - -o - | aws-crypto -d -i - -o -

• $encrypted = 'hello' | aws-crypto -e -m key=$cmkArn -i - -o -
  $encrypted | aws-crypto -d -i - -o -

Converting the intermediate output to base 64 doesn't help. Neither does changing the $OutputEncoding automatic variable to UTF-8.

[mattsb42-aws]

This will be addressed by #29.