test: add more tests including journey test

[simonsan]

Adds more tests, including a journey test for starting and ending activities in different time zones

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 82.35294% with 3 lines in your changes are missing coverage. Please review.

Project coverage is 46.8%. Comparing base (20856fd) to head (8e66f00).

Additional details and impacted files

| [Files](https://app.codecov.io/gh/pace-rs/pace/pull/102?dropdown=coverage&src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pace-rs) | Coverage Δ | | |---|---|---| | [crates/core/src/commands/reflect.rs](https://app.codecov.io/gh/pace-rs/pace/pull/102?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pace-rs#diff-Y3JhdGVzL2NvcmUvc3JjL2NvbW1hbmRzL3JlZmxlY3QucnM=) | `0.0% <ø> (ø)` | | | [crates/core/src/domain/activity.rs](https://app.codecov.io/gh/pace-rs/pace/pull/102?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pace-rs#diff-Y3JhdGVzL2NvcmUvc3JjL2RvbWFpbi9hY3Rpdml0eS5ycw==) | `58.4% <100.0%> (ø)` | | | [crates/core/src/storage/in\_memory.rs](https://app.codecov.io/gh/pace-rs/pace/pull/102?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pace-rs#diff-Y3JhdGVzL2NvcmUvc3JjL3N0b3JhZ2UvaW5fbWVtb3J5LnJz) | `45.7% <ø> (ø)` | | | [crates/time/src/duration.rs](https://app.codecov.io/gh/pace-rs/pace/pull/102?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pace-rs#diff-Y3JhdGVzL3RpbWUvc3JjL2R1cmF0aW9uLnJz) | `80.0% <66.6%> (+0.9%)` | :arrow_up: | | [crates/time/src/date\_time.rs](https://app.codecov.io/gh/pace-rs/pace/pull/102?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pace-rs#diff-Y3JhdGVzL3RpbWUvc3JjL2RhdGVfdGltZS5ycw==) | `44.5% <84.6%> (+7.4%)` | :arrow_up: |