Moves the checks that projects have been configured for desktop to a lower level, where they will cover more codepaths (e.g., 'run'), and improves them to check for native build projects, rather than just directories, to catch cases where the directory exists (e.g., due to accidental creation of generated files).

Also adds links to the error messages pointing to instructions on adding desktop support to a project.

Fixes #47145

* 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

* implicit-casts:false on flutter_tools/lib

* address review comments

* use castStringKeyedMap

* introduce {bool,string,strings}Arg

* fix ci

Moves files generated in windows/flutter/ as part of the build to an ephemeral/ subdirectory, matching the approach used on macOS (and in the future, Windows).

Adds that directory to the generated properties file to minimize hard-coding of paths in the project.

When building in profile or release mode on desktop, add a prominent
warning that it's actually a debug build. This is to help address issues
with people being unaware of the current state of builds due to
following third-party guides rather than official documentation.

macOS is not included since PRs are in flight for macOS release support.

* Improve Windows build failure message

* Undo dartfmt to match source formatting

* Removed prompt to file new issue per PR change request

Slight cleanup of file locations in flutter_tools
to make it easier to see which files are responsible
for data reporting.

- Adds desktop projects to ApplicationPackageStore
- Plumbs target overrides through the desktop builds

Moves the logic for finding vcvars64.bat to a new VisualStudio class
that encapsulates finding, and providing information about, VisualStudio
installations. Adds a validator for it, and runs it for Windows
workflows in doctor.

The props file used in the Windows build didn't include the local engine
build flags when applicable.

Switch from building Runner.vcxproj to Runner.sln on Windows, to allow
for multiple-project builds (e.g., separate plugin projects).

Rather than hard-coding a set of locations to check, use vswhere (which
is installed by VS 2017 and later), and construct the vcvars64.bat path
relative to that. This will allow Windows builds to work without special
configuration for people who have VS installed at a custom path.

Also adds error logging with different messages for each failure point,
so that rather than the not-very-informative 'failed to find
vcvars64.bat' message, the failure will provide feedback about what to
do.

This is an interim solution; later this will be replaced by a
VisualStudio class with associated validator to match the structure of
the other toolchains.

Fixes #33249

Invoking msbuild with runInShell makes handling path escaping more
error-prone, and substantially increases the chances of running into
maximum path limits. This replaces the direct call with a .bat wrapper
that calls vsvars64.bat then msbuild, and uses relative paths within the
script to keep command lengths short.

Fixes https://github.com/flutter/flutter/issues/32792

Allows Windows builds to use the same structure and script as Linux
builds now use, calling into tool_backend to manage copying resources to
the project directory and building the bundle.

Also switches from expecting name_update.bat to expecting flutter\exe_filename
to be written during the build, as with the recent changes to the macOS build, to
reduce the amount of boilerplate needed in a windows\ project directory.

Eliminates the need for a build.bat in the Windows build workflow, adding
preliminary support for building using msbuild. The handling of
vcvars64.bat may be refined in the future, but this serves as a starting point.