Add ability to run any command by reading commit message

[bahmutov]

• Run or skip any command based on platform
• when running a command, set environment variables from commit message

[bahmutov]

Version 1.2.0 has been published to NPM. The full release note can be found at commit-message-install/releases/tag/v1.2.0.

Tip: safely upgrade dependency commit-message-install in your project using next-update