Implement an example control point program examples/ex_control_points.c using action "Wait for trigger".

Project
This is part of Improving concurrency testing determinism (ICTD) in SPM-3857.

Testing
This jira ticket is the first ticket in which the control point framework is complete enough that it can execute and be tested.

Code review
This jira ticket is the the first ticket that is code reviewed. The code review includes all the work so far: this ticket and all the tickets that this ticket depends upon. Those earlier tickets were not code reviewed since the framework was not complete enough yet.

Configuration parsing and Ticket sequence
To allow testing to begin sooner configuration parameter values are hard-wired within their configuration parsing functions which actually do not parse configuration strings at all. Configuration parsing is the next ticket WT-13569. The ticket after that is real world use of control points ticket WT-13541.

Time periods
Note, the control points implementation tickets are in three time periods:

1. POC - Part of the POC.
2. MVP - Part of the minimal viable product. However, even the POC can be used, but less conveniently than the MVP.
3. Future - Enhancements after the MVP.

The title of each ticket starts with the time period.