fix: #113 dispose _typeAheadController only if it has been created inside FormBuilderTypeAheadState

[MickaelTitecaTAO]

Connection with issue(s)

Close #113

Solution description

Use the same logic than https://github.com/flutter-form-builder-ecosystem/flutter_form_builder/blob/main/lib/src/fields/form_builder_text_field.dart

Screenshots or Videos

To Do

• Read contributing guide
• Check the original issue to confirm it is fully satisfied
• Add solution description to help guide reviewers
• Add unit test to verify new or fixed behaviour
• If apply, add documentation to code properties and package readme

[codecov]

Codecov Report

❌ Patch coverage is 50.00000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 56.13%. Comparing base (c615cdc) to head (ab708d6).

Files with missing lines	Patch %	Lines
lib/src/fields/form_builder_typeahead.dart	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #154      +/-   ##
==========================================
- Coverage   56.39%   56.13%   -0.27%     
==========================================
  Files           5        5              
  Lines         211      212       +1     
==========================================
  Hits          119      119              
- Misses         92       93       +1     

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[deandreamatias]

Thanks for contribution!