[feat] upgrade to text 2.0

[MangoIV]

• convert from ut8 based text to utf16 based CString
• use modern test framework to replace old one
• add nix setup
• remove some unnecessary files
• add github actions setup
• setup cabal project to adhere to conventions

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PR Submission Checklist for internal contributors

• The PR Title

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References

1. https://sparkbox.com/foundry/semantic_commit_messages
2. https://github.com/wireapp/.github#usage
3. E.g. feat(conversation-list): Sort conversations by most emojis in the title #SQPIT-764.

[pcapriotti]

Looks good. Minor comment below.