Add BasicWriteTest benchmark

As discussed at [0], this simple benchmark is all about adding a node of type nt:folder at each iteration (run) with an nt:file node which in turn contains an nt:resource node. The last node has a binary property of 5MB (random content generated every time).

[0] https://lists.apache.org/thread.html/ae6eeb41db1e1a92c8cee0dd8edf4fcbf51d14769cfd71d91dc39f84@%3Coak-dev.jackrabbit.apache.org%3E