Changes

Work in progress: moving Opds from app datasource to school datasource.

Work in progress: convert App List screen to using Opds publications instead of Respect App Manifest.

Work in progress: convert App List screen to using Opds publications instead of Respect App Manifest.

Work in progress: model Respect App manifest using OPDS.

Add database migrations.

Add architecture and system to handle Opds for both external sources (eg. compatible apps) and internal (school playlists).

Work in progress making OpdsFeed a writable entity as per other entities in the school database.

Work in progress making OpdsFeed a writable entity as per other entities in the school database.

Implement write support for OpdsFeed including handling etag and last-modified header for non-RESPECT generated feeds.

Add OpdsFeed validation helper implementation.

Make OpdsFeed writable to handle playlists: work in progress.

1) Update OpdsRespectRepositoryIntegrationTest.kt to use OpdsFeedDataSource
2) Update LaunchAppUseCase to use an OpdsPublication instead of a RespectAppManifest.

Update documentation on OpdsFeedDataSource on how external/internal data is handled.

Make Opds Feed writable: make initial working client - server integration test.

Move OpdsPublication data source to follow same naming pattern.

Update OpdsPublicationDataSourceRepository to follow pattern as per OpdsFeedRepository.

OpdsPublicationDataSource improvements

Fix mistake in query that prevented links on publication being saved correctly into database.

Update OpdsPublicationDataSourceHttp.kt so it can handle RespectAppmanifest and convert into an OpdsPublication.

Improvements to handling OpdsPublication and OpdsFeed / related entities.

Put writing/reading of OpdsFeed and Opds in transactions.

Ensure app dependency injection provides validation helpers for http fetching of OpdsFeed and OpdsPublication (ensure that if-modified-since/if-none-match work as expected).

Add 304 response support to UstadCacheImpl.

When a request to the cache includes its own http validation info (if-not-modified since and/or if-none-match), and the response is the cache is fresh, then the cache itself can reply immediately with an empty 304 not modified response.

Add unit test for UstadCache to verify 304 response is returned correctly when incoming request has validation info.

Update UstadCacheInterceptor.kt to respond 304 directly if the underlying request has its own cache validation info and a stale response is validated over the network.

Add test checking 304 not modified response received using interceptor if cache validation headers are used.

Remove CompatibleApp Datasource (replaced by using OpdsPublication).

Remove CompatibleAppEntity from database.

Fixes for AppLauncher screen.

Update opds packages in datasource-db and datasource-http to use school.opds package.

Update database migration files.