FindBoost: Add support for Boost 1.78

Update the list of known versions.

Run the command

    cmake -DBOOST_DIR=/path/to/boost_1_78_0 \
      -P Utilities/Scripts/BoostScanDeps.cmake

to extract dependencies from the 1.78.0 source tree.

The dependencies differ from those of 1.77:

* The `log` component no longer depends on `date_time`.

Fixes: #23016