Support for using ponyup on Windows

[chalcolith]

Ponyup on Windows creates batch files in its bin directory to select the current version of its tools. This PR changes ponyc.exe in make.ps1 to ponyc, which will correctly call ponyup's batch file.

It also makes build the default command for make.ps1.

[ponylang-main]

Hi @kulibali,

The changelog - added label was added to this pull request; all PRs with a changelog label need to have release notes included as part of the PR. If you haven't added release notes already, please do.

Release notes are added by creating a uniquely named file in the .release-notes directory. We suggest you call the file 213.md to match the number of this pull request.

The basic format of the release notes (using markdown) should be:

## Title

End user description of changes, why it's important,
problems it solves etc.

If a breaking change, make sure to include 1 or more
examples what code would look like prior to this change
and how to update it to work after this change.

Thanks.

[SeanTAllen]

Once this has release notes and is merged, I'll do a corral release.