fix(ir): Add support for byte format in string validation

[k4n4ry]

Fixes #1261

Overview

I've added a new Byte field to the String structure in the validate package.
This field is set to true when format: byte is specified in the string formats of OpenAPI.
When executing character length validation, if the Byte field is true, the length is verified using []byte instead of []rune.

Note

This change may not be necessary.
According to the OpenAPI specification, format: byte is specified for base64-encoded characters.
If the characters used are those in base64 encoding, the length evaluation doesn't change during the []byte -> string -> []rune conversion process.
However, as mentioned in the issue, I suppose this change is necessary if we want to ensure validation behavior for more general bytes fields.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 73.93%. Comparing base (829c6a4) to head (63919c9).
⚠️ Report is 722 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1296      +/-   ##
==========================================
+ Coverage   73.90%   73.93%   +0.02%     
==========================================
  Files         189      189              
  Lines       12855    12860       +5     
==========================================
+ Hits         9501     9508       +7     
+ Misses       2805     2804       -1     
+ Partials      549      548       -1     

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[ernado]

I think this should be opt-in.