Add Istio 0.4.0 ( https://istio.io )

[MPV]

After making all changes to the cask:

• brew cask audit --download {{cask_file}} is error-free.
• brew cask style --fix {{cask_file}} reports no offenses.
• The commit message includes the cask’s name and version.

Additionally, if adding a new cask:

• Named the cask according to the token reference.
• brew cask install {{cask_file}} worked successfully.
• brew cask uninstall {{cask_file}} worked successfully.
• Checked there are no open pull requests for the same cask.
• Checked the cask was not already refused in closed issues.
• Checked the cask is submitted to the correct repo.

[commitay]

Rejected Casks
The app is both open-source and CLI-only (i.e. it only uses the binary artifact). In that case, and in the spirit of deduplication, submit it first to Homebrew/core. If it is rejected there, you may then try again in Homebrew-Cask (link us to the issue on Homebrew so we can see their reasoning for rejection).

[MPV]

@commitay: Thanks for reviewing this.

You can find Istio (as binary at least) rejected by Homebrew/core here: Homebrew/homebrew-core#16586 (and it was suggested by someone to be a Cask instead).

[commitay]

You can find Istio (as binary at least) rejected by Homebrew/core

Homebrew formulas build software from source.

Please submit this to Homebrew/core building from source or consider creating your own tap.