BulkLoad should check key/value size before loading it

[saintstack]

See https://forums.foundationdb.org/t/bulkdump-failed/5016?u=saintstack

Scenario: Create SST files including oversized key/value manually. Then, bulkload the SST files. Then, bulkdump the data.

Since bulkload bypasses the transaction system, the bulkload can directly write oversized key/value to the database. This is particularly dangerous in the presence of adversarial SSTs.

BulkLoad mechanism must perform SST file content check when the SST file pass across the boundary of FDB cluster.

Ref: FDB only allows key with the max size KEY_SIZE_LIMIT and value with the max size VALUE_SIZE_LIMIT.