Fix migrations (#133)

* Added calendar id to subscription

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Dao: use specific update methods

* Fixed calendar id removal

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Fixed calendar matching

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Added url to calendar properties

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Fixed calendar id find

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Fixed test

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Fixed subscription id fetching

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Move LocalCalendar, LocalEvent to separate package

* Introduce MANAGED_BY_DB column to control migration

* Fix migration test

* Use NULL/NOT NULL for COLUMN_MANAGED_BY_DB

* Handle v2.1 migrations (don't double-migrate)

* Test migration from 2.0.3 and 2.1

* More logging during migration

* Improve migration tests

Also closes #135

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Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>
Co-authored-by: Ricki Hirner <hirner@bitfire.at>