SqliteSchemaMigration

Non-destructive schema migration shared by every SQLite DB in the SDK (#306, #309).

Until 26.10.2 every SDK DB used (int) LibraryInfo.VERSION_CODE as its version and dropped all its tables in onUpgrade/onDowngrade, so every SDK update (and every rollback) wiped them: the unsent upload queue and map cache (#306), the user's favourites and recently viewed places, location-marketing campaign state, property metadata, diagnostics and map overlays (#309).

The fix, per DB: the version is a constant LEGACY_VERSION_CODE_CEILING + revision that changes only when a table's CREATE SQL changes, and onUpgrade/onDowngrade call reconcileColumns for each table (rows kept) and then onCreate (CREATE TABLE IF NOT EXISTS for any table that was missing).