Upgrades dependencies and The Example app

[Crucialjun]

Updates Flutter FormBuilder to v9.5.0 and associated dependencies.

Upgrades Gradle to 8.9 and Android Gradle Plugin to 8.7.2. Sets NDK version to 27.0.12077973. Updates various Gradle properties for compatibility. Updates Kotlin version to 2.0.0 and other dependencies for compatibility with Flutter 3.24+.

Connection with issue(s)

Close #???

Connected to #???

Solution description

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

Attention: Patch coverage is 80.00000% with 1 line in your changes missing coverage. Please review.

Project coverage is 41.42%. Comparing base (d7b4c20) to head (34e8c4d).
Report is 6 commits behind head on main.

Files with missing lines	Patch %	Lines
lib/src/form_builder_phone_field.dart	80.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #72      +/-   ##
==========================================
+ Coverage   37.85%   41.42%   +3.57%     
==========================================
  Files           1        1              
  Lines         140      140              
==========================================
+ Hits           53       58       +5     
+ Misses         87       82       -5     

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[deandreamatias]

Really thanks for this update. Is important to maintain the package.
After merge, I will test and update some others parts, if necessary, to release a new major version