Add the ability to ability to skip deploying no-op functions

[TheIronDev]

This function adds the ability to skip deploying functions that have not changed.

A common usecase for this is a user that only updated their hosting files (/public) and then ran firebase deploy.

Actionable Items:

• [x] Hash function
• [x] Hash used .env
• [x] Hash secret versions
• [ ] Add a firebase-cli-upload-hash label
• [ ] Fetch the labels of the latest uploaded function
• [ ] Short-circuit upload if hashes match
• [ ] Skip short-circuit if the user has --force
• [ ] Display cli messaging informing functions were not updated (but they can force it)

[inlined]

Please ping when I should give this another look.

[TheIronDev]

Closing this pull request while I implement functionality in smaller chunks.