Add homebrew formula for octez

What

Add a homebrew formula for octez.

Why

To compile octez using homebrew on macOS and linux.

How

Manually testing the MR

Looking for MacOsx testers !

Install brew ( requires sudo, curl, git, build-essentials ):

/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"

Reference brew from the local user:

(echo; echo 'eval "$(/home/linuxbrew/.linuxbrew/bin/brew shellenv)"') >> $HOME/.bashrc
eval "$(/home/linuxbrew/.linuxbrew/bin/brew shellenv)"

run brew:

brew install -v scripts/packaging/Formula/octez.rb 

Checklist

• Document the interface of any function added or modified (see the coding guidelines)
• Document any change to the user interface, including configuration parameters (see node configuration)
• Provide automatic testing (see the testing guide).
• For new features and bug fixes, add an item in the appropriate changelog (docs/protocols/alpha.rst for the protocol and the environment, CHANGES.rst at the root of the repository for everything else).
• Select suitable reviewers using the Reviewers field below.
• Select as Assignee the next person who should take action on that MR