MB-12612 Anomalous Test Framework + Graceful DiskOutOfSpace handling

Fix disk-out of space error handling by not asserting in forestdb layer
but rather propogating error to caller
Redirect filemgr_ops to filemgr_ops_anomalous to create new anomalous
test framework infrastructure where system calls can fail selectively
based on the test suite.
+add new basic write failure anomaly tests
Change-Id: I2375492da5d9e5e0a378fb898adb3986895552c0