Add endpoint `POST /users/sync`

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 22.97297% with 57 lines in your changes are missing coverage. Please review.

Project coverage is 66.65%. Comparing base (d78dfaa) to head (494592b).

Files	Patch %	Lines
infrastructure/external/traq.go	0.00%	22 Missing :warning:
infrastructure/repository/user_impl.go	8.69%	21 Missing :warning:
...repository/mock_repository/mock_user_repository.go	0.00%	8 Missing :warning:
util/mockdata/model.go	0.00%	3 Missing :warning:
usecases/service/user.go	0.00%	2 Missing :warning:
util/mockdata/handler.go	0.00%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #656 +/- ## ========================================== - Coverage 67.00% 66.65% -0.36% ========================================== Files 64 64 Lines 4755 4783 +28 ========================================== + Hits 3186 3188 +2 - Misses 1522 1548 +26 Partials 47 47 ``` | [Flag](https://app.codecov.io/gh/traPtitech/traPortfolio/pull/656/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=traPtitech) | Coverage Δ | | |---|---|---| | [integration](https://app.codecov.io/gh/traPtitech/traPortfolio/pull/656/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=traPtitech) | `66.65% <22.97%> (-0.36%)` | :arrow_down: | | [unit](https://app.codecov.io/gh/traPtitech/traPortfolio/pull/656/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=traPtitech) | `66.65% <22.97%> (-0.36%)` | :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=traPtitech#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.