[Fix] Slight refactor of render part

[YuriRomanowski]

Description

We are going to work hard on translate/render modules and I would like some refactor to be present in all of that PRs beforehand.

Changes:

1. Remove button from section builders as it's never needed;
2. Add separate datatype for sender flag instead of plain Bool;
3. Replace plain text with markdown in the Slack section block;
4. Add functions for converting to offset time/back;
5. Unite fields of TimeReferenceToUtcResult for convenience.

Related issue(s)

Fixed #

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