Separate class for synchronous API

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 76.00000% with 12 lines in your changes missing coverage. Please review.

Project coverage is 75.02%. Comparing base (369c9fa) to head (57de108). Report is 7 commits behind head on main.

Files	Patch %	Lines
src/desktop_notifier/sync.py	75.00%	12 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #145 +/- ## ========================================== - Coverage 75.03% 75.02% -0.01% ========================================== Files 8 9 +1 Lines 833 869 +36 ========================================== + Hits 625 652 +27 - Misses 208 217 +9 ``` | [Flag](https://app.codecov.io/gh/samschott/desktop-notifier/pull/145/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=SamSchott) | Coverage Δ | | |---|---|---| | [pytest](https://app.codecov.io/gh/samschott/desktop-notifier/pull/145/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=SamSchott) | `75.02% <76.00%> (-0.01%)` | :arrow_down: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=SamSchott#carryforward-flags-in-the-pull-request-comment) to find out more.

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.