test typescriptification - backup.spec (matrix-org#2468)

* renamed:    spec/unit/crypto/crypto-utils.js -> spec/unit/crypto/crypto-utils.ts

* ts fixes in crypto-utils

* renamed:    spec/unit/crypto/backup.spec.js -> spec/unit/crypto/backup.spec.ts

* ts fixes in backup.spec

* remove fit

* remove debug

Author: Kerry