* Reland: [flutter_tools] File system utilities

* Remove unused imports

This reverts commit 03496606.

[flutter_tool] Refactor Logger and Terminal to (mostly) no longer depend directly on context (#47269)

Revert "[flutter_tool] Prevent accidental calls to io.exit when asserts are active in unit tests (#46210)" (#46630)

This reverts commit b698c9d7.

* 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

This re-applies the changes that were made in #33697 and #33729,
but which were reverted in #33792 and #33790, respectively due to
the Dart SDK not having received the update within Google yet.
The SDK has now rolled, so these changes can be re-applied.

https://github.com/flutter/flutter/issues/32374
https://github.com/flutter/flutter/issues/33791

https://github.com/flutter/flutter/issues/33791

https://github.com/flutter/engine/compare/69ebe5fb28fc..68a3ca46b40a

git log 69ebe5fb28fca271b23010d43d4dc7f6e5286c4f..a4b7d1c2895d82228705a021cdb7fdb2f71ac2a5 --no-merges --oneline
4c6253cdd Copy the macOS podspec during builds (#9158)
68a3ca46b Roll src/third_party/dart 445a23a9bc..0e6b74543c (29 commits) (#9159)
1d1cff1fa Roll src/third_party/skia 3cd435eecf5e..09f5aedf2cc8 (3 commits) (#9160)

The AutoRoll server is located here: https://autoroll.skia.org/r/flutter-engine-flutter-autoroll

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

If the roll is causing failures, please contact the current sheriff (cbracken@google.com), and stop
the roller if necessary.

These are essentially self-inflicted race conditions. Instead of timeouts we're going to try a more verbose logging mechanism that points out when things are taking a long time.

This reverts commit 76f70810.

* Remove many timeouts.

These are essentially self-inflicted race conditions. Instead of timeouts we're going to try a more verbose logging mechanism that points out when things are taking a long time.

* Get the attach tests to pass.

* Apply review comments from Todd

* More review comment fixes

* Put back the extended timeouts here now that I know why we have them...

This changes the compiler output for gradle to be less verbose and more easily read.

This only applies to compilation error messages: other gradle messages will continue to print as before.

It also fixes a small problem with the performance measurement printing (see that "7.1s" on it's own line in the original?) so that if something is expected to have multiple lines of output, it prints an initial line, and a "Done" line with the elapsed time, so that it's possible to know what the time applies to.

It also updates the spinner to be fancier, at least on platforms other than Windows (which is missing a lot of symbols in its console font).

Addresses #17307