[CDRIVER-4637] A config settings command (#1289)

* New config settings code and defaults.

Almost all setting values have remained the same, and most setting
handling logic has remained unmodified, but this will serve as a basis
for better configuration settings handling in the future tasks for
CDRIVER-4637.

* Aside: message() cleanup

Using `message()` without a mode argument will write the message
as a NOTICE to stderr. We want to use STATUS as the default, which goes
to stdout. Systems which colorize stderr output would seemingly-randomly
color certain lines where the mode argument was missing.

* Use new CMake in more build tasks

Several build tasks still relied on older find-cmake logic. With the
new CMake changes, a more recent CMake version is required. These
tasks and scripts have been updated to use the same logic to find
the same CMake version as is used in the main build tasks.

* Don't use Batch scripts to compile for MinGW

Batch scripting is fraught with peril and wi...