Handle setting time in bulk import FATE operation

[keith-turner]

After the changes in #3350 the bulk import code no longer sets the tablet time for bulk imported files. This can be done using conditional mutations when the tablet is offline (piggy backing on existing conditional mutations) OR by a new RPC when the tablet is hosted to request allocation of a timestamp.

[keith-turner]

In BulkNewIT there is a disabled test (was disabled in #3350). When this is fixed that test can be enabled.

[dlmarion]

ScanConsistencyIT is also failing because of this.

[dlmarion]

The test in BulkNewIT mentioned above is no longer Disabled, however setting time for hosted tablets still does not work. Likely need to add a test in BulkNewIT for this condition.

[keith-turner]

In #4045 setting time was implemented for bulk imports against hosted tablets. However this is not complete, still need to persist this time in a follow in PR.