fix using tab (\t) as separator for custom type names

[nitram509]

Describe the PR

A bug fix.

What happened

• using swag version v1.8.12
• did run swag fmt ... and custom type names got reformatted
• did run swag init ... - Problem: types for custom names not found anymore

Hint: the swag fmt reformats the comment, using a tab (\t) as a separator between @name and the type name.

Expectation

After running swag fmt, the parser still finds all types.

Solution

I did rework the parser using some little regEx to use any kind of whitespace.
An additional test is provided as well.

---

Relation issue
Issue #1150 seems somewhat related, but I don't care what the fmt command does, rather the problem, the parser can't find custom types.

Additional context

I did run go run github.com/swaggo/swag/cmd/swag@latest fmt yesterday, on a larger code base and afterward all custom type names could not be found anymore. The parser did complain can't finding the type.

[codecov]

Codecov Report

Patch coverage: 71.42% and project coverage change: -0.04 ⚠️

Comparison is base (ea35767) 83.80% compared to head (f2d4697) 83.76%.

❗ Current head f2d4697 differs from pull request most recent head fa1ceeb. Consider uploading reports for the commit fa1ceeb to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1594      +/-   ##
==========================================
- Coverage   83.80%   83.76%   -0.04%     
==========================================
  Files          19       19              
  Lines        3747     3752       +5     
==========================================
+ Hits         3140     3143       +3     
- Misses        520      521       +1     
- Partials       87       88       +1     

Impacted Files	Coverage Δ
types.go	93.75% <71.42%> (-6.25%)	⬇️

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