Generates a Property Sheet for Windows builds containing link and include path
information for any included plugins. This allows automating part of the process
of integrating plugins into the build that is currently manual.
To support this change, refactored msbuild_utils into a PropertySheet class so that
it can be used to make different property sheets.
* Update project.pbxproj files to say Flutter rather than Chromium
Also, the templates now have an empty organization so that we don't cause people to give their apps a Flutter copyright.
* Update the copyright notice checker to require a standard notice on all files
* Update copyrights on Dart files. (This was a mechanical commit.)
* Fix weird license headers on Dart files that deviate from our conventions; relicense Shrine.
Some were already marked "The Flutter Authors", not clear why. Their
dates have been normalized. Some were missing the blank line after the
license. Some were randomly different in trivial ways for no apparent
reason (e.g. missing the trailing period).
* Clean up the copyrights in non-Dart files. (Manual edits.)
Also, make sure templates don't have copyrights.
* Fix some more ORGANIZATIONNAMEs
...because otherwise, processes that think they're manipulating your
filesystem will be doing crazy things the test is ignoring, leading to
(at best) failures and (at worst) flakes or disk corruption.
