Rename bytes-from-string decoders

[czechboy0]

Motivation

Fixes #14 - the naming was a bit inconsistent, as it's not decoding "hex bytes" from a "string", but instead "bytes" from a "hex string".

Modifications

Renamed types:

• Base64ByteFromStringDecoder -> ConfigBytesFromBase64StringDecoder
• HexByteFromStringDecoder -> ConfigBytesFromHexStringDecoder

Result

Better names.

Test Plan

Updated tests.

[czechboy0]

Indeed, we're knowingly breaking API here pre-1.0:

8 breaking changes detected in Configuration:
  💔 API breakage: var ConfigBytesFromStringDecoder.base64 has declared type change from Configuration.Base64BytesFromStringDecoder to Configuration.ConfigBytesFromBase64StringDecoder
  💔 API breakage: accessor ConfigBytesFromStringDecoder.base64.Get() has generic signature change from <Self where Self == Configuration.Base64BytesFromStringDecoder> to <Self where Self == Configuration.ConfigBytesFromBase64StringDecoder>
  💔 API breakage: accessor ConfigBytesFromStringDecoder.base64.Get() has return type change from Configuration.Base64BytesFromStringDecoder to Configuration.ConfigBytesFromBase64StringDecoder
  💔 API breakage: var ConfigBytesFromStringDecoder.hex has declared type change from Configuration.HexByteFromStringDecoder to Configuration.ConfigBytesFromHexStringDecoder
  💔 API breakage: accessor ConfigBytesFromStringDecoder.hex.Get() has generic signature change from <Self where Self == Configuration.HexByteFromStringDecoder> to <Self where Self == Configuration.ConfigBytesFromHexStringDecoder>
  💔 API breakage: accessor ConfigBytesFromStringDecoder.hex.Get() has return type change from Configuration.HexByteFromStringDecoder to Configuration.ConfigBytesFromHexStringDecoder
  💔 API breakage: struct Base64BytesFromStringDecoder has been removed
  💔 API breakage: struct HexByteFromStringDecoder has been removed