* Revert "Reverting package changes until I can figure out how to fix Windows. (#14007)"
This reverts commit 6fda8ee821.
* Make prepare_package run on Windows
* Revert "Fixed output validation. (#14005)"
This reverts commit d84398db72.
* Revert "Update package prep script to do async process execution and emit output as it happens. (#13918)"
This reverts commit b7169c1d95.
- Switches to async process execution, which now shows output as it happens instead of in chunks when the process completes
- Now uses ProcessManager so that it may be mocked for the test.
- Adds in the download and install of mingit on Windows.
- Updated package dependencies because of added dependency on process package.
This adds our self-compiled copy of the MinGit executable (built from the flutter/git repo) to the archive when building an archive for Windows.
I also tweaked the internal API for prepare_package.dart so that there's a single entry point to build an archive.
This is the first step in a two-step process of moving the package preparation step from a recipe in chrome_infra to a dart script in the flutter repo. This will make it easier to make changes to the process. The second step is to change the infra recipe to call this script.
In addition, I added a step to the packaging process to run flutter create for each type of template so that any pub dependencies of the templates get added to the cache that gets packaged (and thus users can run flutter create --offline and have it work).
Note that the actual packaging into a "tar" or "zip" file now happens here, so a developer could actually run this script on their machine to create a package.
