Make all checksum mismatches handled same

Currently (1.7.x releases) the "included" (inlined) checksums produce "soft fail" and resolver goes for download of remote external checksum. In 1.8.x line where we added 3rd checksum kind (provided), all 3 of kinds should be treated equally.

Also improve error message, it was: Checksum validation failed, expected BAD but is cf43b5391de623b36fe066a21127baef82c64022 but make it tell more: Checksum validation failed, expected 'BAD' (PROVIDED) but is 'cf43b5391de623b36fe066a21127baef82c64022' (actual)

(added single quotes around checksums and tell their origin)