Deprecate the pieceinfo database, and start storing piece info as a header to
piece files. Institute a "storage format version" concept allowing us to handle
pieces stored under multiple different types of storage. Add a piece_expirations
table which will still be used to track expiration times, so we can query it, but
which should be much smaller than the pieceinfo database would be for the
same number of pieces. (Only pieces with expiration times need to be stored in piece_expirations, and we don't need to store large byte blobs like the serialized
order limit, etc.) Use specialized names for accessing any functionality related
only to dealing with V0 pieces (e.g., `store.V0PieceInfo()`). Move SpaceUsed-
type functionality under the purview of the piece store. Add some generic
interfaces for traversing all blobs or all pieces. Add lots of tests.
* first round cleanup based on go-critic
* more issues resolved for ifelsechain and unlambda checks
* updated from master and gocritic found a new ifElseChain issue
* disable appendAssign. i reports false positives
* re-enabled go-critic appendAssign and disabled lint check at code line level
* fixed go-critic lint error
* fixed // nolint add gocritic specifically
* Space and bandwidth allocation check
* use proper config flag
* one more check + tests
* use monitor to check space and bandwidth
* remove unused field
* check during read/write
* fix linter
* fix pieceid
* remove unused methods
* revert unneeded change