Add support for Tizen 6.5 bindings and automated generation scripts

[seungsoo47]

• Add generate_ffigens.py to automatically generate ffigen_*.yaml config files.
• Add generate_tizen.py to automatically generate lib/<version>/tizen.dart.
• Generate tizen 6.5 specific ffigen configurations.
• Generate tizen 6.5 binding code and symbols.
• Create the lib/6.5/tizen.dart for tizen 6.5 APIs.
• Update scripts/README.md with detailed instructions on using the new generation scripts.

[gemini-code-assist]

Note

Gemini is unable to generate a review for this pull request due to the file types involved not being currently supported.

[JSUYA]

#60
I am reviewing this patch again. Since this structure may need to be reverted, please stop working on additional versions.