add github actions for CI. (#662)

add github actions for CI. (#662)

* add github actions for CI.

* fix shellcheck issues in ci_install_windows.sh

* generalize windows ci build support

cleanup powershell scripts with Invoke-ScriptAnalyzer, including use of
"-Settings CodeFormatting".

create staging directory for windows installer creation.
It is difficult to exclude all the files in the build directory that we don't
want to distribute as the files are a function of the build system.

add windows cmake build.