SubGhz: add GFSK modulation, refactoring subghz_chat

[Skorpionm]

What's new

• SubGhz: subghz_tx_rx_worker, add GFSK modulation
• SubGhz: subghz_chat, refactoring
• SubGhz: subghz_chat, add UTF-8 support

Verification

• Compile and download
• Take more flippers, download subghz_chat and pee in different languages

Checklist (do not modify)

• PR has description of feature/bug or link to Confluence/Jira task
• Description contains actions to verify feature/bugfix
• I've built this code, uploaded it to the device and verified feature/bugfix

[github-actions]

Please fix following code formatting errors:

./applications/subghz/helpers/subghz_chat.h:17:19: error: code should be clang-formatted [-Wclang-format-violations]
} SubghzChatQueue;
                  ^

You might want to run docker compose exec dev /syntax_check.sh for an auto-fix.

[github-actions]

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