fix(data_connect)!: Correct UTF-8 decoding for international characters

[ska2519]

Description

Previously, text containing characters from languages such as Korean, which are encoded in UTF-8, was not being decoded correctly. This resulted in characters appearing garbled or "broken".

This commit updates the decoding logic to properly handle UTF-8 encoding, ensuring correct display and processing of international text.

Related Issues

[firebase_data_connect] Response data Correct UTF-8 decoding for international characters Fixes #17290

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[MichaelVerdon]

Hey there thanks for the PR! Can you please add some tests for this PR?

[ska2519]

@MichaelVerdon Thanks for the review! I've added test cases to cover the UTF-8 decoding change.

[MichaelVerdon]

@MichaelVerdon Thanks for the review! I've added test cases to cover the UTF-8 decoding change.

Thank you this looks good! Can I get you to change 'final' to 'const' to shut the CI up. Happy to do this myself if need be. Then I am happy to approve this. 🥳

firebase_data_connect:
Analyzing ....

   info - test/src/network/rest_transport_test.dart:118:7 - Use 'const' for final variables initialized to a constant value. Try replacing 'final' with 'const'. - prefer_const_declarations

1 issue found.

[ska2519]

@MichaelVerdon Done, I've changed 'final' to 'const' to fix the lint warning. Thanks for the suggestion!

[MichaelVerdon]

Looks good to me