Breaking change #46497: Print VM help and version output to stdout

[Ben Konyi]

Current Behavior

Currently the following invocations output details to stderr instead of stdout:

• dart --help --disable-dart-dev
• dart --help --verbose
• dart --version

Most UNIX tools, as well as other language implementations such as python3 output their help messages to stdout, and some tools like less are typically used by piping stdout as input.

Intended Behavior Change

Update dart to print help and version information to stdout instead of stderr.

Expected Impact
Tooling and tests which scrape stderr for version information or VM flags will start to fail. Impacted tooling and tests will need to be updated to scrape this information from stdout.

Questions?

Please reach out with questions or concerns about this change on the tracking issue: dart-lang/sdk#46497