### Summary
This pull request fixes an issue in which all observation-related endpoints were returning results sorted by `id` (https://github.com/wormhole-foundation/wormhole-explorer/issues/358). The expected behavior is to sort results based on descending timestamp order instead.
Also, swagger docs were updated to document this behavior.
### Summary
* On all endpoints, fix the behavior of the `page` parameter (which was previously being ignored).
* On `GET /api/v1/vaas`, fix the behavior of the `sortBy` parameter (which wasn't working when `parsedPayload=true`).
* For all endpoints, validate the query parameters `page`, `pageNumber` and `sortOrder`.
* Return descriptive errors when pagination-related parameters happen to be invalid (`page`, `pageSize`, `sortOrder`).
* Validate guardian addresses in query params.
### Testing plan
All parameters involved were manually tested.
### Summary
Split `/v1` and `/api/v1` controllers into different packages (respectively `api/routes/guardian` and `api/routes/wormscan`).
Still need to move services/repositories/models according to the new package layout.