We determined in WT-12343 that TSan can be brought online for WiredTiger, and will be bringing it online over the course of multiple tickets. This is the first ticket in the batch and will be adding an evergreen test that runs example/c/ex_hello with TSan enabled.

Since this is the first ticket testing under TSan test it will also include some initial frameworking for resolving TSan warnings; A TSan suppression file and new atomic_store/atomic_load functions.

Enabling TSan gives us better confidence about our multi-threaded code and helps detect data races that could cause code correctness issues. As part of this work we're changing many non-atomic accesses to memory to instead use relaxed atomic operations, which removes the potential for data racing.