Create cpp test for prefix search near entries

The idea of this test is to make a cppsuite test to validate the search optimisation provided by prefix_key configuration. The prefix search near should only traverse the prefix portion of the search key in the tree.

Definition of the test:
1. Have a initial populate phase which will insert a set of keys with prefix aaa -> zzz
2. Spawn multiple read threads and validate the prefix search near optimisation through checking the statistics WT_STAT_CONN_CURSOR_NEXT_SKIP_LT_100 for the number of entries we have traversed during a search near, and WT_STAT_CONN_CURSOR_SEARCH_NEAR_PREFIX_FAST_PATHS if we have done a prefix search near early exit.

This test will also have user configurable options e.g. read thread count, key size, number of collections, number of entries per prefix.