Add options to support byte string map keys as struct field names

[benluddy]

Description

Introduces one encode option and one decode option to control the CBOR major type of struct field names.

The current behavior on encode is to produce text strings for field names, unless a field has the keyasint tag option, in which case it will serialize as either a positive or negative CBOR int. That remains the default encode behavior, with the new option to produce byte strings instead of text strings for fields that do not have the keyasint tag option.

Decoding a CBOR map containing a byte string key into a Go struct value currently produces an error. By overriding the default value of the new decode option, byte string map keys can also be recognized as struct field names.

PR Was Proposed and Welcomed in Currently Open Issue

• This PR was proposed and welcomed by maintainer(s) in issue feature: Options to support byte string map keys as struct field names #471
• Closes or Updates Issue feature: Options to support byte string map keys as struct field names #471

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[fxamacker]

Nice! 👍 Thanks for opening this PR!

I left a couple of comments (one is my fault about naming option) and a small optimization is possible.

Thanks again!

[benluddy]

Thanks for the feedback, @fxamacker! I applied both of your suggestions.

[fxamacker]

LGTM! 👍 Many thanks!